Effects Of Rosiglitazone Combined With Insulin Therapy On Islet β Cell Function And The Level Of Serum GLP-1 In Type 2 Diabetic Patients

Objective: To investigate the effects of rosiglitazone(RSG) combined with insulin therapy on islet β cell function, especially on early phase of insulin secretion, and on the secretion of glucagon-like peptide-l(GLP-1) in type 2 diabetic patients who need to use insulin therapy to control blood glucose. Methods: Type 2 diabetic patients who need to use insulin therapy were selected. Matched-control study(1:1) was used, according to age, sex, diabetic duration, glycosylated hemoglobin A_1C (HbA_1C) ,and so on. One is study group and the other is control group. The study group injected insulin and combined with RSG(4 mg/day) orally, the control group only used insulin. The therapy lasted for 3 months. 100g carbohydrate (steamed bread) challenge of C-peptide(CP) releasing test was performed to evaluate β cell function. Other indices such as serum GLP-1(0min, 30min, 120min), HbA_1C, tumor necrosis factor(TNF) - α , urinary ratio of albumin to creatinine (UA/Cr), free fat acid(FFA),triglycerides(TG), high density lipoproteincholesterol(HDL-ch) and low density lipoprotein cholesterol(LDL-ch) were detected.Results: Thirty patients were included in the study and 28 patients finished follow-up. At the end, in the study group serum levels of TG decreased[ (1.98 ±1.20vs 1.61 + 0.72) mmol/L, p=0.049], HDL-ch increased [(1.15 + 0.23 vs 1.36 + 0.28) mmol/L, p<0.001], FFA decreased[(663.14 + 88.18 vs 499.48 + 94.36) ummol/L, p<0.001] significantly; in the control group these indices did not change significantly. The diastolic pressure in the study group was decreased [(77.14+12.45 vs 74.50 + 5.92)mmHg,p=0.008], the blood pressure of control group did not have significant changes. Indices of early phase insulin secretion in the study group were improved significantly [CP30min(0.63 + 0.23 vs 0.84 + 0.33) mmol/L, p=0.002, AUCcp3O(15.51 + 6.05 vs 19.85 + 7.19) mmol.min. I/',p=0.000, A CP30/ A G30(0.07 + 0.05 vs 0.14 + 0.10,p=0.02)]. Other indices of 3 cell function were also improved [CPOmin (0.40 + 0.18 vs 0.49 + 0.20) mmol/L, p=0.031, CP120min(0.94 + 0.39 vs 1.17 + 0.45) mmol/L, p=0.002, AUCcpi20(85.94 +30.78 vs 110.37 + 38.26),p=0.000]. Some indices of GLP-1 in the study group were increased significantly [GLP-13on?(24.45 + 1.23 vs 25.60 + 1.13)pmol/L, p=0.000, AUCglp30(637.82 + 53.60 vs 659.68 ± 50.25)pmol.min.L^!,p=0.000, AUCglp,20(2601.43 +184.41 vs 2686.29+171.07) pmol.min.L-'^O.OOO]. TNF -a [(7.92 + 1.60 vs 7.12 + 1.00) fmol/L, p=0.032] and ratio of UA/Cr [(42.59 + 27.43 vs 35.81+25.66) ug/mg, p=0.047] in the study decreased significantly, and these indices in the control group did not change significantly. Conclusion: Rosiglitazone may improve islet P cell function includingearly phase of insulin secretion in type 2 diabetic patients. Effects of RSG on 3 cell function in type 2 diabetic patients may relate to the improvement of IR, the protective function of RSG on $ cell, otherwise might relate to the increase of GLP-1 secretion.