Improvements in insulin sensitivity and β‐cell function (HOMA) with weight loss in the severely obese

Abstract Aims To examine the effect of weight loss on insulin sensitivity and β‐cell function in severely obese subjects of varying glycaemic control. Patients and methods Subjects were 254 (F:M 209:45) patients having adjustable gastric banding for severe obesity, with paired biochemical data from before operation and at 1‐year follow up. The homeostatic model assessment method was used to calculate insulin sensitivity (HOMA%S) and β‐cell function (HOMA%B). Subjects were grouped by diabetic status and by pre‐weight loss HbA 1c . Results Initial mean ( sd ) weight and body mass index were 128 (26) kg and 46.2 (7.7) kg/m 2 , respectively, and at 1‐year were 101 (22) kg and 36.4 (6.7) kg/m 2 . The percentage of excess weight lost (%EWL) was 44.3 (14)%. HOMA%S improved from 37.5 (16)% presurgery to 62 (25)% ( P < 0.001). %EWL was the only predictor of HOMA%S improvement ( r = 0.28, P < 0.001). Subjects with normal fasting glucose, impaired fasting glucose and Type 2 diabetes had a fall, no change and increase in HOMA%B, respectively. The improvement in HOMA%B in subjects with diabetes ( n = 39) was inversely related to the time with diabetes ( r = −0.36, P = 0.02). In non‐diabetic subjects the HOMA%S–HOMA%B relationship was favourably altered with weight loss, so that for any given HOMA%S there was an increase in HOMA%B ( f = 11.8, P = 0.001). This improvement in HOMA%B was positively related to %EWL ( r = 0.25, P = 0.019). Discussion There are beneficial changes in both insulin sensitivity and β‐cell function with weight loss. Modern laparoscopic obesity surgery may have an important early role in the management of Type 2 diabetes in obese subjects.