Melatonin improves glucose homeostasis in young Zucker diabetic fatty rats

: The aim of this study was to investigate the effects of melatonin on glucose homeostasis in young male Zucker diabetic fatty (ZDF) rats, an experimental model of metabolic syndrome and type 2 diabetes mellitus (T2DM). ZDF rats (n = 30) and lean littermates (ZL) (n = 30) were used. At 6 wk of age, both lean and fatty animals were subdivided into three groups, each composed of ten rats: naive (N), vehicle treated (V), and melatonin treated (M) (10 mg/kg/day) for 6 wk. Vehicle and melatonin were added to the drinking water. ZDF rats developed DM (fasting hyperglycemia, 460 ± 39.8 mg/dL; HbA1c 8.3 ± 0.5%) with both insulin resistance (HOMA‐IR 9.28 ± 0.9 versus 1.2 ± 0.1 in ZL) and decreased β‐cell function (HOMA1‐%B) by 75%, compared with ZL rats. Melatonin reduced fasting hyperglycemia by 18.6% (P