| Backgrounds and ObjectivesSex hormone-binding globulin (SHBG), a kind of glycoprotein produced by liver, could conjugate and transfer sex hormones specifically, and thus control the levels of bioavailable sex hormones in blood. SHBG could bind testosterone with high affinity and estrogen with lower affinity, so it was thought to be a marker of androgenicity. Associations had been shown between sex hormone-binding globulin and several risk factors of type 2 diabetes mellitus, such as obesity, central fat distribution, increased blood glucose, hyperinsulinemia and insulin resistance. Nestler had proposed that SHBG might be a marker of hyperinsulinemic insulin resistance. The links between SHBG and type 2 diabetes have not been conclusive though in some studies an association between SHBG level and type 2 diabetes mellitus had been reported. In several prospective studies, the reduced SHBG could predict the development of type 2 diabetes mellitus independently. The causality between them is being debating. Pioglitazone is one of the insulin-sensitizing compounds,2001 %-thiazolidinediones. Thiazolidinediones were thought to improve insulin sensitivity through the activation of peroxisome proliferator-activated receptor y (PPARy), the suppression of lipogenic TNFa production and the facilitation of GLUT-4 expression.The aims of the study were: 1) To examine the levels of serum SHBG and sex hormones in patients with type 2 diabetes compared with normal persons who were matched by sex, age, BMI, BP and blood lipids; 2) To observe the associations between serum concentration of SHBG and several risk factors such as ISI, FBG, BMI, etc in patients with type 2 diabetes; 3) To examine the levels of serum SHBG, etc after pioglitazone intervention.Subjects and MethodsWe recruited 85 cases with type 2 diabetes (38 women cases were postmenopausal) of participants in II phase clinical study of pioglitazone. They were randomized into two groups i treatment group (pioglitazone+SU+BD) and placebo group (placebo+SU+BD). A 12-week double-blind placebo controlled study was conducted in them. Serum samples were taken before and after 12-week study. The 59 control serum samples were collected from participants of physical examination matched by age, sex, BP, BMI, cholesterol and triglyceride. Serum SHBG were measured with IRMA, and serum total E2, total T, FINS were detected with RIA. I/ (FBG*FINS) was used to evaluate insulin sensitivity. All results were analyzed by SPSS 10.0.Results1) Compared with control groups, diabetic groups had lower fasting blood glucose, fasting blood insulin, insulin sensitivity index and Homa B cell index significantly; while their sex, age, BP, BMI, cholesterol, triglyceride were matched with control groups.2) Diabetic groups had lower serum SHBG levels significantly compared with control groups of both sexes (women, P<0.01; men, P<0.05), especially in women. Serum total estradiol of women diabetic group was higher than that of women control group, but this difference was not significant (P=0.063). No significant difference was seen in serum total testosterone of both sexes, T/SHBG were significantly higher in diabetic women than that in normoglycemic women (P<0.01). While in men, this difference was not observed.3) In women diabetic group, serum SHBG was negatively correlated with fasting blood glucose and fasting insulin (coefficients were -0.372, P0.05; -0.332, P<0.05), And there was a significant positive correlation between serum concentration of SHBG and insulin sensitivity index (coefficient was 0.445, P<0.01). While no significant correlation was seen between SHBG and BMI.4) In men diabetic group, BMI was negatively correlated with seram SHBG and total testosterone (coefficients were - 0.329, P0.05 and - 0.424, P<0.01). Whlie no significant correlation was seen between serum SHBG and insulin, insulin sensitivity index and fasting blood glucose,5) About treatment group of women, FBG, HbAiC and CHO, TG, HDL-C, LDL-C were significantly improved co... |
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