Objective: Our aim was to distinguish beneficial effects of B-cell rest from other effects of correction of hyperglycaemia. For this purpose we used diazoxide which reversibly blocks insulin secretion.
Material and methods: Eight obese (age 53 +/- 1 yr: BMI 33 +/- 2 kg/m2: 4 females) type 2 diabetic patients with poor metabolic control (HbA1c 8.7 +/- 0.9% ref.<5.2%) were studied twice after a randomly ordered treatment period of five days of intensive i.v. insulin treatment alone or i.v. insulin with peroral diazoxide (300 mg/day, divided into 3 doses). The glycaemic control was not altered between the two treatment periods. Insulin secretion was measured in response to i.v. glucose and arginine.
Results: Insulin infusion was used to achieve close to identical degrees of glycaemia during the two treatment periods. Previous treatment with diazoxide was associated with a moderate 1.9 +/- 0.6 fold rise in insulin response to intravenous glucose (p=0.04) and 1.6 +/- 0.4 fold increased glucose potentiation of arginine-induced insulin secretion (GPAIS) (p=0.04). Conversely, after insulin alone there was no response to i.v. glucose and no change in GPAIS.
Conclusions: Short-term diazoxide treatment improved important parameters of B-cell function and these effects could be dissociated from confounding effects of changes in glycaemia. Consequently, the results indicate beneficial effects of B-cell rest.