Diabetic rats

The rats were fasted 12 h before the streptozotocin (STZ)-nicotinamide (NA) injection. T2DM was induced by the intraperitoneal (i.p) administration of a single dose (65 mg/kg BM) of STZ freshly dissolved in 0.1 M citrate buffer (pH = 4.5), 15 min after i.p administration of 110 mg/kg BM of NA dissolved in normal saline. Animals were allowed to drink 20% glucose solution overnight to overcome drug-induced hypoglycemia. Rats in the pair-fed (PF) group were i.p injected with an equal volume of citrate buffer and normal saline. Hyperglycemia was confirmed according to the levels of fasting blood glucose (FBG), which was determined in day 3 and 7 after injection. Rats with FBG levels above 13.9 mmol/L were considered to T2DM in the experiment [19], followed by feeding various types of diets.