Relevance between endogenous creatinine clearance rate and islet β-cell function in type 2 diabetic patients

Abstract

Objective To investigate the relevance between islet β-cell insulin secretion,insulin sensitivity and endogenous creatinine clearance rate (Ccr,ml · min-1· 1.73-1 m-2) in type 2 diabetic patients.Methods Four-hundred and thirty-two cases of type 2 diabetic patients were enrolled,including 123 cases with normal renal function(90 ≤Ccr＜ 130),80 cases with glomerular hyperfihration (Ccr≥130),145 cases with mild renal dysfunction(60≤Ccr＜90)and 84 cases with moderate and severe renal dysfunction(Ccr＜60).Oral glucose tolerance and insulin releasing test were performed.The insulin resistance was evaluated by the ratio of area under curve of insulin to area under curve of glucose (AUCI/AUCG) and homeostasis model assessment for insulin resistance (HOMA-IR).The insulin sensitivity was reflected by insulin sensitivity index(ISI) and Matsuda ISI.The homeostasis model assessment for β-cell function (HOMA-β),early insulin secretion index (△I30/△G30),the second-phase insulin secretion index (AUCI)and disposal index (DI)were calculated to estimate islet β-cell secretary function.The differences between clinical and biochemical parameters were compared among the four groups,and the correlation between Ccr and IR was analyzed.Results (1) Compared with the normal renal function group,the HOMA-IR in the groups with mild,moderate and severe renal dysfunction was significantly higher(P＜0.01),while the ISI and Matsuda ISI were significantly lower(P＜0.01).The AUCI/AUCG in the groups with moderate and severe renal dysfunction was higher than that in the other three groups(P＜0.05).(2)The AUCI in the groups with moderate and severe renal dysfunction was higher than that in the other three groups (P＜0.05).The DI in the groups with mild,moderate and severe renal dysfunction was significantly higher than that in the normal renal function group(P＜0.05).(3)Ccr was negatively correlated with the course of diabetes,systolic blood pressure,diastolic blood pressure,AUCI,HOMA-IR,AUCI/AUCG(P＜0.05) and was positively correlated with ISI and Matsuda ISI(P＜0.01).Multiple stepwise regression analysis showed that Ccr was negatively correlated with systolic blood pressure,course of diabetes and AUCI/AUCG.(P ＜ 0.05).Conclusions Ccr is negatively correlated with insulin resistance,so insulin resistance may be an independent risk factor of renal dysfunction in patients with type 2 diabetes. Key words: Diabetes mellitus，type 2; Creatinine clearance rate; Insulin sensitivity; Insulin resistance; Islet β-cell secretary function