Effect of small intestine exclusion surgery on oral glucose tolerance test in Goto-Kakizaki rats with type II diabetes mellitus

Abstract

Objective To investigate the effect of small intestine exclusion surgery on blood glucose and oral glucose tolerance test (OGTT) in Goto-Kakizaki (GK) rat with type Ⅱ diabetes mellitus.Methods 40 GK rats were randomly divided into 5 groups:duodenal bypass (Group A,n = 8),duodenaljejunal bypass (Group B,n = 8),duodenum and total jejunum exclusion (Group C,n = 8),sub-total small intestine exclusion (Group D,n = 8),and sham-operation (Group SO,n=8).All rats were observed for 24 weeks after surgery.Fasting blood glucose was tested at 0,1,3,6,12,and 24 wk.OGTT was performed at 0,1,and 24 wk.After the administration of 3 g/kg glucose by oral gavage,blood glucose was measured in conscious rats before (baseline) and after 30,60,120,and 180 minutes.Areas under curves (AUC) were calculated by trapezoidal integration.Results Rats in group A,B,C and D had lower fasting blood glucose levels and better oral glucose tolerance as shown by lower peak and area-under-thecurve (AUC) glucose values through the entire follow-up period[group B (fasting blood glucose:(9.0±2.4) mmol/L vs.(4.4±1.0) mmol/L;OGTT peak:(20.8±3.1) mmol/L vs.(10.3±2.0) mmol/L;AUC:(2658±417) mmol·min/L vs.(1324±317) mmo·min/L,P ＜0.05 or P ＜0.01].Fasting blood glucose had no differences before 12 wk and significantly increased at 12 (9.1±2.4) mmol/L and 24 wk (10.0±2.3) mmol/L in group SO (preoperative values were (8.1±1.9) mmol/L,P ＜ 0.01.There was no differences in oral glucose tolerance as shown by lower peak and area-under-the-curve (AUC) glucose values between 0 and 1 wk (P＞0.05),while the oral glucose tolerance become worse as shown by the delay of peak,higher peak (25.6±2.0) mmoL/L vs.(21.4±2.7) mmoL/l,and AUC (3422±360) mmol·min/L vs.(2667±377) mmol·min/L.Glucose values in group SO at 24 wk compared to preoperatively (P＜0.01).Rats in group A,B,C,and D had lower fasting blood-glucose and better oral glucose tolerance compared with sham-operated group through the entire follow-up period (P＜0.05 or P＜0.01).Rats in group B had lower fasting blood-glucose and better oral glucose tolerance compared to those in group A while the effect on diabetes control in group B,C and D were similar to one another (P＞0.05).Conclusion Small intestinal exclusion containing proximal gut was effective for glucose control and improving gucose tolerance,duodeno-jejunal bypass may be applicable for diabetes control in clinical setting. Key words: Diabetes mellitus,Type 2; Gastroenterostomy; Blood glucose; Glucose tolerance test