ABSTRACT
Plasma obestatin level was determined in patients with impaired glucose regulation and type 2 diabetes mellitus.The plasma obestatin levels in patients of both groups were significantly decreased as compared with that in controls.Plasma obestatin level was negatively correlated with body mass index,HbA_(1C),waist-to-hip ratio,plasma insulin and HOMA-IR.Obestatin level seems to be related with metabolic disorder.
ABSTRACT
Objective To investigate the effects of pioglitazone on glucose metabolism,circulating resistin and adiponectin concentrations,and tissue resistin levels in rats with insulin resistance induced by free fatty acid (FFA).Methods A hyperinsulinaemic-euglycaemic clamp and[3-~3H]-glucose tracing technique were used in awake rats.Insulin-mediated peripheral and hepatic glucose metabolism,plasma resistin and adipenectin levels, resistin levels in tissues were assessed by hyperinsulinaemic-euglycaemic clamp with elevation of FFA by lipid infusion over 4 h in rats pretreated with or without pioglitazone.Results During steady-state of clamp,there was a significant increase in plasma FFA in lipid-infused group(L group)and pioglitazone-pretreated lipid-infused group(P/L group)compared to control rats(P＜0.01).The glucose infusion rate(GIR)in P/L group was significantly reduced as compared with controls[(20.6?0.9 vs 33.6?1.5)mg?kg~(-1)?min~(-1),P＜0.01], whereas the GIR was lower in L group than in P/L group[(12.6?0.8 vs 20.6?0.9)mg?kg~(-1)?min~(-1),P＜0.01].As compared with baseline,the hepatic glucose production(HGP)was significantly suppressed by 85% [(18.3?2.1 vs 2.7+2.4)mg?kg~(-1)?min~(-1) and (17.5?2.6 vs 2.6?1.0)mg?kg~(-1)?min~(-1),both P＜0.01]during the hyperinsulinaemic clamp in control and P/L groups.The suppressive effect of insulin on HGP was significantly blunted in L group[(17.3?2.1 vs 15.8?1.5]mg?kg~(-1)?min~(-1)].The rate of glucose disappearance(G_(Rd))was reduced in L group and P/L group compared with controls(P＜0.01).Baseline plasma resistin level was lower in P/L group than that in the controls[(7.8?1.3 vs 29.1?3.1)?g/L,P＜0.01].After lipid infusion,plasma resistin levels significantly increased in P/L group,but remained lower than that of L group [(18.1?3.8 vs 47.0?2.2)?g/L,P＜0.01].Baseline adiponectin level was higher in P/L group than those in the controls and L groups[(3.9?0.2 vs 2.8?0.1 and 2.6?0.2)mg/L,P＜0.01].After clamp,plasma adiponectin levels were decreased in L group and L/P group compared with baseline(both P＜0.05).In addition, the resistin level in the liver of P/L group decreased compared with the controls and L groups(both P＜0.05), whereas significantly increased in the muscle of L group.Conclusion Lipid infusion induces an acute insulin- resistance in vivo.Pioglitazone pretreatment partly prevents FFA-induced insulin resistance possibly by changing resistin and adiponectin levels.