The invention provides a composition for improving type 2
diabetes mellitus complicated with depression as well as a preparation method and application of the composition, and relates to the technical field of medicines. The composition comprises the following components: a
coptis chinensis extract, a hawthorn leaf extract, L-
carnitine, acetyl L-
carnitine and
inulin. The
coptis chinensis is subjected to first-time enzymolysis by using a compound
enzyme 1, and then is subjected to second-time enzymolysis by using a compound
enzyme 2; and after enzymolysis, performing ultrasonic-assisted extraction by using an
ethanol solution to obtain the
coptis chinensis extract. Carrying out first enzymolysis on the hawthorn by using a compound
enzyme 3, and then carrying out second enzymolysis by using a compound enzyme 4; and after enzymolysis, carrying out
microwave-assisted extraction by using an
ethanol solution to obtain the hawthorn leaf extract. The composition has a synergistic effect of all the components in the aspects of improving the glucose
metabolism function and depression behavioristics, can effectively reduce fasting blood glucose,
insulin resistance indexes and glycosylated
hemoglobin, increase the sweet water preference rate and shorten the immobility time of
forced swimming and
tail suspension experiments, and has a better effect of treating
diabetes mellitus complicated with depression.