[Benefits and limitations of protein diets in obese patients with type 2 diabetes].

Weight excess plays a major role in the pathophysiology of type 2 diabetes but only a minority of patients succeed in following a restrictive calorie diet in the long-term, able to reduce body weight and maintain normoglycaemia. Very low-calorie diets such as protein diets rapidly reduce plasma glucose levels by various mechanisms, among which a significant improvement of hepatic and muscular insulin sensitivity and a partial recovery of insulin secretion. The rapidity of the hypoglycaemic action suggests that calorie restriction plays a more important role than weight loss itself. The lowering of plasma glucose levels imposes an early reduction in the doses of antidiabetic agents to avoid hypoglycaemia. Well-balanced protein diets are well tolerated, provided that they are restricted to a few weeks. The most important limitation of the protein diet is the risk of weight regain afterwards and such situation requires the maintenance of an hypocaloric diet in the long-term. Ideally, the protein diet should be integrated in a global approach including treatment of obesity, type 2 diabetes and frequently associated other risk factors.