This study hypothesised that fermented mealworm extract (TMP) with higher amino acid contents than nonfermented extract can be used as a dietary protein source for type 2 diabetes mellitus, and compared its effects with casein (CA) using C57BLKS/J-db/db mice. TMP marginally lowered serum insulin and leptin levels and hepatic triglyceride, and lipid droplets compared with CA group. Proteomic analysis showed that 14 proteins (H4C1, CYB5A, ANXA5, RGN, 40S ribosomal protein, Atp2, PDI, GRP78, RDX, GCH1, LDHA, GNMT, ACAA2, and UROC1) were up-regulated and 8 proteins (UQCRC1, Txndc5, SBP2, HSPA8, PHB, TF, PC, and PK) were down-regulated in the CA group compared to the normal mice. However, TMP significantly down-regulated ANXA5, RGN, Atp2, PDI, RDX, LDHA, ACAA2, and UROC1, and up-regulated UQCRC1, PHB, TF, and PK. These proteins are related to glycolysis, lactate production, fatty acid β-oxidation, oxidative stress, and endoplasmic reticulum stress. These results suggest that TMP is a potential protein source that can replace CA in type 2 diabetes.

Mealworms (Tenebrio molitors larvae) have a high quality and quantity of amino acids and protein that have attracted attention as an alternative nutrition resource. This study examined the anti-hyperglycemic effects of fermented mealworm extract (MWF) in db/db mice. The mice were fed with or without MWF for six weeks. MWF was administered orally to the mice at 200 mg/kg body weight/d. MWF improved the fasting blood glucose level and glucose intolerance significantly compared to the control group. Insulin immunohistochemistry staining showed that the insulin levels of pancreatic β-cells in the MWF group were higher than those of the control group. MWF increased the hepatic glycogen content and the related gene levels, such as glucose transporter 2 and glycogen synthase 2. Thus, MWF lowered the blood glucose levels by up-regulating glucose uptake and glycogen synthesis-related gene expression. These results suggest that MWF can be used as a new natural anti-diabetic resource for type 2 diabetes.