Detecting reinsertion of a continuous glucose monitoring sensor

Abstract

A continuous glucose monitoring (CGM) system is configured to detect a reinserted CGM sensor. In response to insertion of the CGM sensor into a user's skin, the system reads an identifier of the CGM sensor stored in the CGM sensor unit memory. The system compares the identifier to any previously stored identifiers of previously inserted CGM sensors. If the identifier does not match the previously stored identifier, indicating a newly inserted sensor, the identifier is stored, and CGM may begin. If the identifier matches the previously stored identifier, indicating a reinserted sensor, the usage restrictions corresponding to the stored identifier of the reinserted sensor are checked to determine whether they have been met. If they have been met, the CGM is stopped. If they have not been met, the CGM may continue with the reinserted CGM sensor. As with other aspects, methods for detecting CGM sensor reinsertion and usage restrictions are also provided.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This invention claims the benefit of U.S. Provisional Patent Application No. 63 / 051,862, filed July 14, 2020, the disclosure of which is incorporated herein by reference in its entirety for all purposes.

[0002] The present invention relates generally to continuous glucose monitoring (CGM). [Background technology]

[0003] CGM has become a routine monitoring operation in diabetes care. By providing real-time glucose readings, therapeutic actions can be applied in a more timely manner and glycemic conditions can be better controlled. During CGM operation, the sensor of the CGM device is typically inserted subcutaneously and operates continuously in an environment surrounded by tissue and interstitial fluid. The sensor inserted under the user's skin provides a signal to the wireless transmitter unit of the CGM device that is indicative of the user's glucose level. Glucose readings can be performed automatically multiple times throughout the day (e.g., every few minutes or at some other pre-established time interval).

[0004] The CGM device may be attached to the exterior surface of the user's skin, such as the abdomen or the back of the upper arm, while the sensor is inserted through the skin and contacts the interstitial fluid. The sensor interacts with the interstitial fluid and generates electrical signals proportional to the amount of glucose present. These electrical signals are communicated to a transmitter unit for use in determining glucose levels.

[0005] CGM devices can be worn on the body for days or weeks before the sensor needs to be removed and replaced. In some cases, the sensor may need to be removed and reinserted, for example, to address issues with the CGM device's adhesion to the user's skin. Summary of the Invention

[0006] In some embodiments, a continuous glucose monitoring (CGM) system is provided that includes a sensor unit having a sensor unit memory and a sensor, the sensor unit memory having an identifier stored therein. The CGM system also includes a second memory configured to store a plurality of sensor identifiers therein. The CGM system further includes a processor in communication with the second memory and the sensor unit. The processor is configured to execute computer instructions to: (1) read the identifier stored in the sensor unit memory; (2) determine whether the identifier matches any previously stored identifiers in the second memory; (3) store the identifier in the second memory in response to the identifier not matching any previously stored identifiers in the second memory; and (4) determine whether the sensor has met a predetermined usage limit in response to the identifier matching the previously stored identifier in the second memory.

[0007] In some embodiments, a continuous glucose monitoring (CGM) system is provided that includes a sensor configured to be inserted into a user's skin and generate an electrical signal indicative of a glucose level. The CGM system also includes a first memory having stored therein an identifier that identifies the sensor, a second memory configured to store therein a plurality of sensor identifiers, and a processor in communication with the first and second memories. The processor is configured to execute computer instructions to: (1) read the identifier stored in the first memory; (2) determine whether the identifier matches any previously stored identifiers in the second memory; (3) store the identifier in the second memory in response to the identifier not matching any previously stored identifiers in the second memory; and (4) determine whether the sensor has met a predetermined usage limit in response to the identifier matching the previously stored identifier in the second memory.

[0008] In some embodiments, a method for detecting reinsertion of a continuous glucose monitoring (CGM) sensor is provided, the method including: in response to activation of the CGM, reading an identifier of the sensor from a sensor unit memory via a processor executing computer instructions, determining whether the identifier matches any previously stored identifiers in a second memory, storing the identifier in the second memory in response to the identifier not matching any previously stored identifiers in the second memory, determining whether the sensor has met predetermined usage limits in response to the identifier matching the previously stored identifiers in the second memory, and ceasing operation of the CGM in response to determining that the sensor has met the predetermined usage limits.

[0009] Further aspects, features, and advantages of the present disclosure will become readily apparent from the following detailed description and illustrations of several exemplary embodiments and implementations, including the best mode contemplated for carrying out the invention. The present disclosure may enable other different embodiments, and its several details may be modified in various respects, without departing from the scope of the present invention. For example, although the following description relates to continuous glucose monitoring, the devices, systems, and methods described below may be readily adapted to monitoring other analytes, such as cholesterol, lactate, uric acid, alcohol, and the like, in other continuous analyte monitoring systems. The present disclosure is intended to cover all modifications, equivalents, and alternatives within the scope of the appended claims (see further below). [Brief explanation of the drawings]

[0010] The drawings described below are for illustrative purposes and are not necessarily drawn to scale. Accordingly, the drawings and descriptions should be regarded as illustrative in nature, and not as restrictive. The drawings are not intended to limit the scope of the invention in any way.

[0011] [Figure 1]1 illustrates a side view of a continuous glucose monitoring (CGM) device including a sensor unit and a transmitter unit according to embodiments provided herein. [Figure 2] 2 illustrates a block diagram of the CGM device of FIG. 1 according to embodiments provided herein. [Figure 3] 1 illustrates a block diagram of a CGM system including a CGM device and an external device, according to embodiments provided herein. [Figure 4] 1 illustrates a flowchart of a method for detecting reinsertion of a CGM sensor, according to embodiments provided herein. [Figure 5A] 10 illustrates a table stored in memory listing CGM sensor identifiers, usage limits, and usage counts, each according to an embodiment provided herein. [Figure 5B] 10 illustrates a table stored in memory listing CGM sensor identifiers, usage limits, and usage counts, each according to an embodiment provided herein. [Figure 5C] 10 illustrates a table stored in memory listing CGM sensor identifiers, usage limits, and usage counts, each according to an embodiment provided herein. DETAILED DESCRIPTION OF THE INVENTION

[0012] To more closely monitor and detect changes in a person's glucose concentration level, continuous glucose monitoring (CGM) methods and systems have been developed. CGM methods and systems typically generate electrochemical glucose signals continuously during operation and perform glucose measurements / estimations based on the generated signals, typically every few minutes.

[0013] CGM systems generally have a wearable portion (CGM device) that is worn on the body and communicates (e.g., wirelessly) with an external device, such as a handheld CGM receiver or other portable device like a smartphone running a suitable application software program. The CGM device may be worn for several days or for one or two weeks before needing to be removed and replaced. The CGM device includes a sensor that is inserted subcutaneously (implanted). The CGM device may also include analog circuitry coupled to the sensor and configured to bias the sensor and measure a current signal generated by the inserted sensor in contact with interstitial fluid. The CGM device may also include processing circuitry for determining a glucose concentration level based on the measured current signal. The CGM device may further include electronic transmitter circuitry for communicating the determined glucose level to an external device (e.g., a smart device or CGM receiver). The CGM device may be attached to an external surface of the skin, such as the abdomen, the back of the upper arm, or another suitable location, for example, via adhesive.

[0014] CGM systems may provide frequent measurements of a user's glucose level without the need for each such measurement to involve drawing a blood sample, such as a finger stick. CGM systems may still occasionally use a finger stick and the use of a blood glucose monitoring (BGM) system, such as the Contour NEXT One® by Ascensia Diabetes Care AG of Basel, Switzerland, to initiate calibration of the CGM system.

[0015] The CGM device of a CGM system may typically be worn for up to about two weeks, after which the sensor may be removed and replaced. In some embodiments, the entire CGM device may be removed and replaced. In another embodiment, the CGM device may include a replaceable sensor unit that can be detached by the user from the reusable transmitter unit of the CGM device. In such an embodiment, only the sensor unit of the CGM device may need to be removed and replaced.

[0016] A CGM system may be configured to notify a user, for example, via a display message and / or an audible alert, when a sensor has reached its usage limit and should be replaced. The CGM system may also prevent glucose measurements from occurring with such an EOL (“end-of-life”) sensor. However, a user may attempt to reuse an EOL sensor by removing the sensor from the user's skin surface and then reinserting it into the skin as if it were new. For numerous health and performance reasons, a CGM system configured to prevent this from happening would be desirable. However, a user may also experience problems with a CGM device during operation, such as problems with the CGM device adhering to the user's skin surface, requiring the user to remove and reinsert the sensor to correct the problem. The CGM system would also be desirable to distinguish this situation from an attempt to reuse an EOL sensor.

[0017] According to one or more embodiments, provided herein are devices, systems, and methods for detecting reinsertion of a CGM sensor and subsequent detection of compliance with its usage restrictions, as described in more detail below in connection with FIGS. 1-5C.

[0018] FIG. 1 illustrates a wearable CGM device 100 inserted into a user's skin 102, according to one or more embodiments. The CGM device 100 is configured to continuously monitor and provide glucose measurements periodically (e.g., every 5 minutes or other suitable time intervals). While the CGM device 100 is shown as partially dome-shaped, the CGM device 100 may have other shapes. The CGM device 100 may include a sensor unit 104 and a transmitter unit 106. In some embodiments, the sensor unit 104 and the transmitter unit 106 may be integrally formed. In other embodiments, the sensor unit 104 may be disposable and detachable from the transmitter unit 106, which may be replaceable and reusable with other sensor units. The sensor unit 104 and the transmitter unit 106 may be physically connected together via any suitable mechanical mechanism. The sensor unit 104 and the transmitter unit 106 may also be electrically coupled together such that, when physically connected, data and control signals may be communicated and transmitted between electrical components within the sensor unit 104 and the transmitter unit 106. In some embodiments, initiation of communication between the sensor unit 104 and the transmitter unit 106 may be in response to physically connecting the two units together. In other embodiments, communication may be initiated by a command, such as a start command. Communication between the sensor unit 104 and the transmitter unit 106 may be initiated in other suitable ways.

[0019] The sensor unit 104 may include a sensor 108, a portion of which is shown to be inserted through the user's skin 102. The sensor 108 may extend from the sensor unit 104 through a base plate 110 and may be configured to reside at least partially within interstitial fluid in the user's subcutaneous region. The sensor 108 may be or include an analyte sensor or analyte sensor portion, such as at or near a sensor tip 108T. The sensor 108 may be inserted with an insertion device (not shown) having a sharp needle or "introducer" that pierces the skin to introduce the sensor 108 into the user's subcutaneous region. Any suitable insertion device may be used.

[0020] The sensor unit 104 may also include an adhesive layer 112, which may be, for example, double-sided tape or a pressure-sensitive adhesive. One side of the adhesive layer 112 may adhere to the base plate 110, while the other side of the adhesive layer 112 may adhere to the user's skin surface 102S.

[0021] The transmitter unit 106 may include one or more electronic components that communicate with one or more electronic components within the sensor unit 104 and with one or more external devices, as described in more detail below.

[0022] 2 illustrates a circuit component configuration 200 of a CGM device 100 according to one or more embodiments. The sensor unit 104 may include a sensor assembly 214 and a sensor unit memory 216. The sensor assembly 214 may include a sensor 108 and a sensor circuit (not shown separately) coupled to the sensor 108. The sensor circuit may apply at least one bias voltage to an analyte sensor portion of the sensor 108, which may generate an electrical signal while the sensor 108 is in contact with interstitial fluid. The sensor circuit may also facilitate conduction of the electrical signal between the sensor tip 108T of the sensor 108 and / or other portions of the sensor 108.

[0023] The sensor unit memory 216 may include programmable read-only memory (PROM), electrically erasable programmable read-only memory (EEPROM), write-once-read-many memory (WORM), static random access memory (SRAM), synchronous dynamic random access memory (SDRAM), physically unclonable function (PUF) (which may serve as a unique identifier), and / or NOR and NAND flash memory. Other suitable types of sensor memory circuits may be used for the sensor unit memory 216.

[0024] In some embodiments, the sensor unit memory 216 may include radiation-resistant memory (rad-hard memory) or may be located in rad-hard packaging that retains information (e.g., data) stored therein when the packaging and / or memory is exposed to radiation used to sterilize the sensor unit 104.

[0025] The sensor unit memory 216 may store sensor information specific to that individual sensor unit and its internal components. For example, the sensor information may include a sensor unit identifier (e.g., the sensor unit's serial number) and corresponding usage restrictions. The identifier may be unique or at least partially unique (e.g., a manufacturer may not reuse the same identifier within a particular time period or particular geographic area, so that a user is unlikely to insert a sensor with the same identifier as a different, recently inserted sensor). The sensor information may include, for example, one or more of the following parameters: a) electrode sensitivity gradient; b) date of manufacture; c) expiration date (storage period), d) batch or lot number; e) Security code, and / or f) Memory device version.

[0026] Other parameters and / or sensor information may be stored in sensor unit memory 216. Additionally or alternatively, some or all of the above parameters and / or sensor information may be encoded, such as in a barcode, on sensor unit 104, CGM device 100, and / or its packaging.

[0027] In some embodiments, electrical data and control signals and power may be transmitted between the sensor unit 104 and the transmitter unit 106 via the connector 218, electrical contact pads 220 and 222 on the sensor unit 104, and electrical contact pads 224 and 226 on the transmitter unit 106 when the sensor unit 104 and the transmitter unit 106 are physically connected together.

[0028] The transmitter unit 106 may include an analog front end 228, a microcontroller 230 (or other similar processing resources), memory 232, a power source such as a battery 234, and a wireless transmitter 236. In some embodiments, the transmitter unit 106 may include a local display (not shown) for displaying information such as glucose concentration information, sensor EOL, sensor expiration date, etc. without the use of an external device.

[0029] The analog front end 228 may be configured to drive the sensor assembly 214 and / or process sensor data generated by the sensor assembly 214 and the sensor 108. For example, the analog front end 228 may be configured to apply a bias voltage to the sensor assembly 214 and measure the resulting current through the sensor assembly 214. The analog front end 228 in conjunction with the sensor assembly 214 may apply a bias voltage to an inserted sensor 108 located in the interstitial fluid and measure the resulting current proportional to the glucose concentration. The analog front end 228 may perform other, fewer, or more functions.

[0030] Microcontroller 230 may be coupled to analog front end 228, memory 232, battery 234, wireless transmitter 236, and possibly other circuitry (not shown). Microcontroller 230 may include a processor, such as, for example, a microprocessor or other suitable processing circuitry, for processing sensor data generated by sensor assembly 214 and / or analog front end 228 and for detecting sensor reinsertion as described herein. Microcontroller 230 may also include, for example, an analog-to-digital converter for converting the analog current signal generated by sensor assembly 214 to a digital current signal. Microcontroller 230 may further store the digital current signal value in memory 232 and / or calculate or estimate a glucose concentration level based at least in part on the digital current signal. Microcontroller 230 may further detect whether a sensor of the CGM device has been reinserted and whether the reinserted sensor has met its usage limitations (e.g., whether its end-of-life (EOL) has been reached), as described in more detail below in connection with FIGS. 4 and 5. Microcontroller 230 may perform other suitable functions.

[0031] The microcontroller 230 and / or other circuitry within the transmitter unit 106 may be electrically coupled to and configured to communicate with the sensor unit memory 216. The microcontroller 230 may receive data stored in the sensor unit memory 216, including an identifier for the sensor unit 104, along with other of the sensor information described above related to one or more parameters of one or more components of the sensor unit 104. In some embodiments, a signal (e.g., a pull signal) may be sent from the microcontroller 230 to the sensor unit memory 216, causing the sensor unit memory 216 to transmit data without user input. Thus, the sensor unit memory 216 may automatically transmit data to the microcontroller 230 in response to connecting the sensor unit 104 to the transmitter unit 106. Alternatively, transmission of sensor information from the sensor unit memory 216 to the microcontroller 230 may occur by prompt, such as from an external device, or in any other suitable manner.

[0032] Microcontroller 230 may store information received from sensor unit memory 216 in memory 232 and may use the information when calculating analyte concentrations, when detecting whether sensor 108 has been reinserted (and if so, whether sensor 108 has met its usage limits), and when performing other functions. In other embodiments, the information may remain in sensor unit memory 216 and may be accessed as needed during CGM processing by microcontroller 230 or other circuitry.

[0033] Additionally or alternatively, the microcontroller 230 and memory 232 may receive sensor information from the sensor unit 104, one or more barcodes on the CGM device 100 and / or its packaging, or the like, via scanning by an external device in communication with the transmitter unit 106.

[0034] The memory 232 may include computer program code stored therein that, when executed by a processor within the microcontroller 230, causes the CGM device 100 to perform various functions and / or communicate with one or more external devices, such as a CGM receiver or smart device (e.g., a smartphone or tablet) running a CGM application software program that may calculate and / or display glucose levels and related data.

[0035] The memory 232 may also be configured to store multiple sensor unit identifiers corresponding to previously used sensor units in embodiments where the sensor unit 104 is replaceable and detachable from the transmitter unit 106 for reuse with other sensor units. In some embodiments, the identifiers corresponding to previously used sensor units may be stored, for example, in cloud-based storage and downloaded to the memory 232 as needed.

[0036] The memory 232 may further include computer program instructions stored therein that, when executed by the processor within the microcontroller 230, cause the CGM device 100 to, in part, determine whether the identifier stored in the sensor unit memory 216 matches any previously stored identifiers within the memory 232, and, in response to determining that the identifier stored in the sensor unit memory 216 matches any previously stored identifiers within the memory 232, determine whether the sensor 108 has met its predetermined usage limits.

[0037] In some embodiments, memory 232 may be radiation-hard memory (rad-hard memory) or may be located in a rad-hard package similar to or the same as sensor unit memory 216. Memory 232 may be non-volatile memory and may include, but is not limited to, electrically programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), and / or flash memory (e.g., a type of EEPROM in either a NOR or NAND configuration). Other types of suitable memory may be used for memory 232, including reading data from an internet storage location, which may be cloud-based.

[0038] The battery 234 may be located in the transmitter unit 106 and may provide power to the transmitter unit 106. In some embodiments, the battery 234 may be rechargeable. When the sensor unit 104 is connected to the transmitter unit 106, the battery 234 may also provide power to the sensor unit 104. Providing power to the sensor unit 104 may, in some embodiments, initiate communication between the sensor unit 104 and the transmitter unit 106, initiate sensor insertion detection, and / or initiate CGM processing. In some embodiments, power may be provided to the sensor unit 104 via the analog front end 228. In other embodiments, the battery 234 may be located within the sensor unit 104 instead of the transmitter unit 106, and in still other embodiments, the sensor unit 104 and the transmitter unit 106 may each have their own battery. Examples of the battery 234 include coin-cell batteries such as flexible lithium polymer batteries, lithium manganese, silver oxide, and alkaline coin cells (e.g., CR2032, SR516, and LR60 type coin cells), etc. Other power supply / battery types may be used.

[0039] In some embodiments, microcontroller 230 may transmit electrical signals, glucose concentration information, and / or other information to one or more external devices via wireless transmitter 236. In some embodiments, microcontroller 230 may receive electrical signals, instructions, data, and / or other information from one or more external devices via wireless transmitter 236.

[0040] 3 illustrates a CGM system 300 according to one or more embodiments. The CGM system 300 includes a CGM device 100 and an external device 330. The external device 330 may be, for example, a dedicated CGM receiver or a smart device running a CGM application software program. The external device 330 may include a processor 332, a memory 334, a wireless transmitter 336, and a display 338, where the processor 332 is coupled to each of the memory 334, the wireless transmitter 336, and the display 338, each of which may be any suitable device or component configured to perform at least some or all of the CGM-related functions described herein. The external device 330 may include other circuit components as well.

[0041] The external device 330 and the CGM device 100 may be communicatively coupled to one another via their respective wireless transmitters 236 and 336. Such wireless communication may occur via any suitable standards-based communication protocol, such as, for example, the Bluetooth® communication protocol. In some embodiments, wireless communication between the external device 330 and the CGM device 100 may occur via near field communication (NFC), radio frequency (RF) communication, infrared (IR) communication, optical communication, or any other suitable type of wireless communication. In some embodiments, the external device 330 and the CGM device 100 may additionally or alternatively communicate via one or more wired connections. In some embodiments, a security code matching a security code stored in the sensor unit memory 216 may need to be entered by the user into the external device 330 before communication can begin between the transmitter unit 106 and the sensor unit 104 and / or between the CGM device 100 and the external device 330.

[0042] In some embodiments, at least a portion of the sensor information stored in the sensor unit memory 216 of the sensor unit 104 may be transferred to the memory 334 of the external device 330 via the wireless transmitter 236 of the CGM device 100 and the wireless transmitter 336 of the external device 330. The received sensor information may be processed by the processor 332 and displayed on the display 338. In some embodiments, some or all of the processing for determining the glucose level may be performed by the processor 332 instead of the transmitter unit 106 and displayed on the display 338. Other sensor information received by the external device 330 may be displayed on the display 338 to the user of the CGM device 100. For example, the manufacturing date and / or expiration date of the sensor 108 and / or sensor unit 104 may be provided to the user, which may allow the user to determine whether to use the sensor unit 104 and / or CGM 100.

[0043] In some embodiments, some or all of the processing for detecting reinsertion of the sensor 108 and determining whether the reinserted sensor has met its usage restrictions as described herein in connection with the transmitter unit 106 may be performed by the external device 330 rather than the transmitter unit 106. Specifically, for example, the memory 334 of the external device 330 may be configured to store multiple sensor unit identifiers corresponding to previously used CGM devices (in embodiments in which the sensor unit 104 and transmitter unit 106 are integrally formed) or previously used sensor units (in embodiments in which the sensor unit 104 is replaceable and detachable from the transmitter unit 106 and reusable with other sensor units). Also, in some embodiments, the sensor information / data may be stored in cloud-based storage and retrieved from there to the memory 334 by the external device 330 as needed. In other embodiments, some or all of the sensor information / data may be encoded, such as in one or more barcodes attached to the sensor unit 104, the CGM device 100, and / or their packaging, and retrieved therefrom to the memory 334 by a scanner (not shown) of the external device 330.

[0044] In embodiments where the sensor unit 104 and transmitter unit 106 are integrally formed, requiring the CGM device 100 to be removed and replaced at the end of life of the sensor 108, an identifier (e.g., serial number) of the CGM 100 may be stored in either the sensor unit memory 216 or the memory 232 of the transmitter unit 106. In some embodiments, a CGM device 100 with an integrally formed sensor unit 104 and transmitter unit 106 may have only a single memory in which the identifier may be stored (e.g., the sensor unit memory 216 and memory 232 may be combined into a single memory device, which may still be referred to as the sensor unit memory). The CGM identifier may be transferred to the memory 334 of the external device 330 in response to insertion or reinsertion of the CGM device 100 into the user's skin.

[0045] The memory 334 of the external device 330 may include computer program instructions, which may be part of an internally stored CGM application software program, that, when executed by the processor 332, cause the processor 332 to, in part, determine whether the identifier stored in the CGM device 100 matches any previously stored identifiers in the memory 334, and, in response to determining that the identifier stored in the CGM device 100 matches any previously stored identifiers in the memory 334, determine whether the sensor 108 has exceeded its predetermined usage limit.

[0046] FIG. 4 illustrates a method 400 for detecting whether a sensor of a CGM device has been reinserted and whether the reinserted sensor has met its usage limitations (e.g., whether its EOL has been reached). At processing block 402, method 400 may begin by reading or receiving a sensor identifier via a processor executing computer instructions in response to CGM activation. CGM activation may occur in response to powering on the sensor unit, in response to a user-entered command, in response to insertion of the sensor into the user's skin, or in any other suitable manner of initiating CGM. The identifier may be stored, for example, in the sensor unit memory of the sensor unit and / or encoded, for example, in a bar code attached to the sensor unit, the CGM device, or their packaging. In some embodiments, the sensor may be sensor 108 of sensor unit 104 of CGM device 100, which may be part of CGM system 300 (see FIGS. 1-3). The sensor unit memory may be sensor unit memory 216 and the processor may be a processor of microcontroller 230 of CGM device 100 or may be processor 332 of an external device 330 in communication with CGM device 100 .

[0047] The method 400 may proceed to decision block 404 to determine whether the sensor identifier matches any identifiers of previously inserted sensors stored in a second memory. The second memory may be, for example, memory 232 located within the transmitter unit 106 of the CGM device 100 or memory 334 of the external device 330. In some embodiments, the second memory may include a table such as that shown in FIG. 5A.

[0048] 5A illustrates a stored table 500A listing sensor identifiers for previously inserted sensors and corresponding usage limits and usage counts. For example, the most recent previously inserted sensor may have an identifier (e.g., serial number) of 12345678, a usage limit of 4032, and a usage count of 4032 (indicating that the sensor has reached its usage limit). In some embodiments, the usage limit may represent a predetermined total number of glucose readings allowed by the sensor. For example, a 14-day sensor that takes glucose readings every 5 minutes would have a usage limit of (12 readings per hour × 24 hours per day × 14 days) 4032. Similarly, a 10-day sensor that takes glucose readings every 5 minutes would have a usage limit of (12 readings per hour × 24 hours per day × 10 days) 2880.

[0049] If the determination is "yes" at decision block 404, the sensor identifier matches a previously stored identifier in the second memory and is therefore presumed to have been reinserted, indicating that it is being reused, and method 400 may proceed to decision block 412 where the usage count corresponding to that sensor identifier is checked to determine whether it meets the usage limit corresponding to that sensor identifier, indicating that the sensor has reached its EOL.

[0050] If the determination is “no” at decision block 404 , indicating that the sensor identifier is not in the second memory, the sensor is presumed to be new and method 400 may proceed to process block 406 .

[0051] In processing block 406, the second memory is updated to include the new identifier, and the usage count of that sensor (presumably new) corresponding to the newly stored identifier is set to zero. For example, referring to FIG. 5B, which illustrates table 500B storing sensor identifiers of previously inserted sensors and corresponding usage limits and usage counts, assume that a newly inserted sensor has identifier 46813527, which does not match any of the previously stored identifiers. In response, the second memory is updated with sensor identifier 46813527 along with its usage limit of 4,032 (which may also be read from the sensor unit memory), as shown in FIG. 5B, and its corresponding usage count is set to zero.

[0052] The method 400 may then proceed to process block 408 where data from the sensor is read and a glucose reading is determined / estimated based on the sensor data, as described above.

[0053] From processing block 408, method 400 may then proceed to processing block 410, where a usage count corresponding to the sensor identifier in the second memory may be updated based on the last glucose reading performed in processing block 408. For example, referring to FIG. 5C, which illustrates a table 500C storing sensor identifiers and corresponding usage limits and usage counts, assume sensor identifier 46813527 represents a currently inserted sensor that just performed a glucose reading. The usage count corresponding to sensor identifier 46813527 may be incremented from 3,679 to 3,680.

[0054] The method 400 may then proceed to decision block 412 to determine whether the sensor's usage limit has been met (indicating that the sensor has reached its EOL) and should no longer be used. For example, referring again to FIG. 5C , the method may reach decision block 412 from either decision block 404 or processing block 410 to determine whether the usage count (e.g., 3,679 or 3,680) meets the usage limit (e.g., 4,032) corresponding to sensor identifier 46813527.

[0055] If the determination is "no" at decision block 412, indicating that the sensor usage restrictions have not been met and therefore it can still be used, method 400 may return to processing block 408 where another glucose reading may be taken at a predetermined measurement interval of the CGM system (e.g., every 5 minutes).

[0056] If the determination is "yes" at decision block 412, indicating that the sensor usage restrictions have been met and therefore the sensor should no longer be used, the method 400 may proceed to process block 414.

[0057] At processing block 414, operation of the sensor is stopped. That is, the processor of the CGM device 100 and / or external device 330 may signal the user with an error message or an audible alert via an I / O device (e.g., a display and / or sound device) of the CGM device 100 and / or external device 330 that glucose monitoring has ceased and the sensor needs to be replaced. In some embodiments, the CGM device 100 and / or external device 330 may prevent the sensor from operating and / or may prevent processing of any signals received from the sensor.

[0058] In alternative embodiments, tables 500A, 500B, and 500C may each include a fourth column to indicate any error, defect, fault, or failure of the sensor, replaceable sensor unit, or replaceable CGM device detected during power-on or use that would prohibit continued use of the sensor, replaceable sensor unit, or replaceable CGM device, regardless of whether the sensor's usage limits are met. In these alternative embodiments, alternative decision block 412 may determine whether any such error, defect, fault, or failure has occurred (as illustrated in the fourth column) in addition to determining whether the sensor's usage limits have been met. In response to a determination that such an error, defect, fault, or failure has occurred or that the sensor's usage limits have been met, alternative method 400 would proceed to block 414 to stop operation of the sensor. In response to a determination that an error, defect, fault, or failure has occurred and the sensor's usage limits have not been met, alternative method 400 would proceed to processing block 408.

[0059] Note that in some embodiments, tables 500A, 500B, and 500C may store only a small number of identifiers (e.g., 5-10) corresponding to recently used sensors. In some embodiments, tables 500A, 500B, and 500C may be stored in memory 232 of transmitter unit 106, while in other embodiments, tables 500A, 500B, and 500C may be stored in memory 334 of external device 330 or in cloud-based memory.

[0060] It is also noted that some embodiments, or portions thereof, may be provided as a computer program product or software, which may include a machine-readable medium having stored thereon non-transitory instructions that may be used to program a computer processor, system, controller, or other electronic device to perform the processes or methods described herein in accordance with one or more embodiments.

[0061] While the present disclosure is susceptible to various modifications and alternative forms, specific method and apparatus embodiments have been shown by way of example in the drawings and are herein described in detail. It will be understood, however, that the specific methods and apparatus disclosed herein are not intended to limit the scope of the disclosure or the claims.

Claims

1. 1. A continuous glucose monitoring (CGM) system comprising: a sensor unit having a sensor unit memory and a sensor, the sensor unit memory storing an identifier and a security code therein; a radio transmitter; and an external device; The external device a second memory configured to store therein a plurality of sensor identifiers; a processor in communication with the second memory and the sensor unit, the processor comprising: reading the identifier stored in the sensor unit memory; determining whether the identifier matches any previously stored identifier in the second memory; storing the identifier in the second memory in response to the identifier not matching any previously stored identifier in the second memory; and identifying a usage count corresponding to said identifier; requiring a user to input the security code into the external device before initiating communication between the sensor and the wireless transmitter, wherein communication between the sensor and the wireless transmitter is prevented when the code input by the user does not match the security code; determining whether the usage count of the sensor has met a predetermined usage limit in response to the identifier matching a previously stored identifier in the second memory, wherein detecting the usage count below the predetermined usage limit allows for an estimation of a glucose level, and incrementing the usage count corresponding to the identifier in response to receiving the glucose level from the sensor.

1. A continuous glucose monitoring (CGM) system configured to execute computer instructions to:

2. The CGM system of claim 1 , wherein the second memory is also configured to store the predetermined usage limit and the usage count for each of the plurality of sensor identifiers.

3. 3. The CGM system of claim 2, wherein to determine whether the sensor has met the predetermined usage limit, the processor is configured to execute computer instructions that determine whether the usage count corresponding to the identifier is equal to the usage limit corresponding to the identifier.

4. The method further includes a CGM device configured to be worn by the user, the CGM device comprising: the sensor unit; 2. The CGM system of claim 1, further comprising: a transmitter unit electrically connected to the sensor unit, the transmitter unit comprising the wireless transmitter and a microcontroller comprising the processor.

5. The CGM system of claim 4 , wherein the sensor unit and the transmitter unit are integrally formed.

6. 5. The CGM system of claim 4, wherein the sensor unit is replaceable and detachable from the transmitter unit so that it can be reused with other sensor units.

7. 2. The CGM system of claim 1, wherein the processor is further configured to execute computer instructions to read sensor data from the sensor unit to estimate the glucose level in response to storing the identifier in the second memory.

8. 8. The CGM system of claim 7, wherein the processor is further configured to execute computer instructions to determine whether the sensor has met the predetermined usage limit in response to an increment in the usage count following reading the sensor data and estimating the glucose level.

9. 8. The CGM system of claim 7, wherein the processor is further configured to read the sensor data from the sensor unit to estimate the glucose level in response to the sensor not meeting the predetermined usage limit.

10. The CGM system of claim 1 , wherein the processor is further configured to execute computer instructions to deactivate sensor operation in response to the sensor meeting the predetermined usage limit.

11. 1. A continuous glucose monitoring (CGM) system comprising: a sensor configured to be inserted into the user's skin and to generate an electrical signal indicative of a glucose level; a first memory having stored therein an identifier and a security code that identifies the sensor; a second memory configured to store therein a plurality of sensor identifiers; a radio transmitter; a processor in communication with the first memory and the second memory, the processor comprising: reading the identifier stored in the first memory; determining whether the identifier matches any previously stored identifier in the second memory; storing the identifier in the second memory in response to the identifier not matching any previously stored identifier in the second memory; and requiring a user to input the security code, and wherein when the code input by the user does not match the security code, preventing communication between the sensor and the wireless transmitter; determining whether the sensor has met a predetermined use limit in response to the identifier matching a previously stored identifier in the second memory, wherein detecting a use count below the predetermined use limit enables an estimation of a glucose level, and incrementing a use count corresponding to the identifier in response to receiving the glucose level from the sensor.

1. A continuous glucose monitoring (CGM) system configured to execute computer instructions to:

12. The CGM system of claim 11 , wherein a CGM device comprises the first memory and an external device comprises the second memory and the processor, or the first memory comprises a sensor unit memory of a sensor unit and the sensor unit comprises the sensor.

13. The CGM system of claim 11 , wherein the first memory or the second memory is cloud-based.

14. 1. A method for detecting reinsertion of a continuous glucose monitoring (CGM) sensor in a CGM device, comprising: In response to activation of the CGM sensor, reading an identifier of the CGM sensor from a sensor unit memory via a processor executing computer instructions; determining whether the identifier matches any previously stored identifier in a second memory; storing the identifier in the second memory in response to the identifier not matching any previously stored identifier in the second memory; and requiring a user to input a code that matches a security code stored in a sensor unit memory, wherein in response to the user inputting a code that does not match the security code, communication between the CGM sensor and a wireless transmitter of the CGM device is prevented; and in response to a user entering a code matching the security code and the identifier matching a previously stored identifier in the second memory, determining whether the CGM sensor has met a predetermined usage limit, wherein a CGM sensor that does not meet the predetermined usage limit updates a usage count corresponding to the previously stored identifier based on current usage of the CGM sensor. ceasing operation of the CGM device in response to determining that the CGM sensor has met its predetermined usage limits.

15. 15. The method of claim 14, further comprising, in response to storing the identifier, setting the usage count corresponding to the identifier to zero in the second memory.

16. 15. The method of claim 14, further comprising estimating a glucose level via the processor in response to reading CGM sensor data via the CGM sensor and storing the identifier.

17. updating the usage count of the CGM sensor in response to the current usage of the CGM sensor; The current use of the CGM sensor is reading the CGM sensor data; estimating said glucose level; 17. The method of claim 16.

18. 18. The method of claim 17, wherein determining whether the CGM sensor has met the predetermined usage limit also occurs in response to updating the usage count.

19. 20. The method of claim 18, wherein reading the CGM sensor data and estimating the glucose level occurs in response to determining that the CGM sensor does not meet the predetermined usage limits.

20. 15. The method of claim 14, further comprising determining whether the CGM sensor has an indication of an error, defect, fault, or failure in response to the identifier matching the previously stored identifier in the second memory.

21. 21. The method of claim 20, further comprising: in response to determining that the CGM sensor has the indication of an error, defect, fault, or failure, ceasing operation of the CGM device.

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