Retinol Binding Protein 4 (rbp4) And Insulin Resistance Study

Objective: To determine the serum level of retinol binding protein 4 (RBP4), and observe the effects of short-term treatment of rosiglitazone on it in no-obese patients with type 2 diabetes mellitus.Methods: 17 no-obese patients with type 2 diabetes who were inadequately controlled by sulfonylureas were treated with rosiglitazone (4mg/d) for 12 weeks. 23 sex-, age- and BMI-matched non-diabetic subjects were studied. Blood pressure, RBP4, triglyceride (TG), high density lipoprotein (HDL-c), low density lipoprotein (LDL-c), fasting plasma glucose (FPG), 2-hour postprandial glucose (PPG) and fasting insulin (FINS) were determinded in all subjects. Furthermore, free fatty acid (FFA), high sensitive C-reactive protein (hsCRP) and glycosylated hemoglobin (HbA1c) and abdominal fat distribution performed before and after treatment with rosiglitazone in diabetic group.Results: 1. Serum RBP4 was higher in diabetic group than that in control group (34.21±4.62 vs. 29.84±4.78, P<0.01), and it was lower after treatment with rosiglitazone for 12 weeks, but that was not significantly different (34.21±4.62 vs. 32.95±4.49, P>0.05); 2. RBP4 was correlated significantly with diastolic pressure(r=-0.31, P=0.017),FPG (r=0.39, P =0.003), PPG (r=0.47, P<0.001), Homa-IR (r=0.46, p<0.001), TG (r=0.38, P=0.004), HDL-c (r=-0.29, P=0.031) and FFA (r=0.41, P=0.017) respectively. However, there was no significant correlation between RBP4 and BMI, abdominal fat distribution, hsCRP or HbA1c; 3. Linear regression analysis for all subjects showed that RBP4 had the significant correlation with TG and PPG (r2=0.31, ?=12.04, P <0.001).Conclusions: 1.The serum level of RBP4 is higher in the type 2 diabetic patients, and it is significantly related with glucose and lipid metabolic factors. 2. The short-term treatment with rosiglitazone can not reduce the serum concentration of RBP4 in no-obese patients with type 2 diabetes. Objective: To determine serum retinol binding protein 4 (RBP4) level and evaluate its association with insulin resistance in women with polycystic ovarian syndrome (PCOS).Methods: 39 PCOS women and 45 control subjects matched with respect to age, waist-to-hip ratio (WHR) and body mass index (BMI), were enrolled in this study. Serum RBP4, fasting plasma glucose (FPG) and fasting plasma insulin (FINS) were measured for all subjects. Furthermore, oral glucose tolerance test (OGTT), Botnia euglycemic hyperinsulinemic clamp test and sex hormones were performed in all PCOS women and 13 control subjects.Results: The serum level of RBP4 was elevated in PCOS women compared with the controls (11.69±6.72 vs. 7.69±5.89μg/ml, P=0.006). Serum RBP4 level was positively correlated with WHR (r=0.216, P=0.048) and intravenous glucose tolerance testβcell index (IVGTT-β, r=0.309, P=0.028), which assessesβcell function, but were inversely correlated with clamp index M, which best represent insulin reisistance status (r=-0.362, P=0.008). No correlation was found between RBP4 and age, BMI, blood pressure, free testosterone, total testosterone, follicle stimulating hormone (FSH) or luteinizing hormone (LH). In a linear stepwise regression analysis with a model including age, BMI, WHR, IVGTT-β, M, FSH, LH, and free testosterone as independent variables, only M showed significant correlation with serum RBP4 levels in all subjects receiving Botnia clamp (r2=0.105,?=6.640,P=0.012).Conclusion: The serum RBP4 level is significantly increased in PCOS women and firmly associated with insulin resistance displayed by Botnia clamp. It indicates that RBP4 may be a contributing factor linking adipose tissue and insulin resistance in PCOS.