Management of type 2 diabetes mellitus with special reference to metformin therapy.
As monotherapy, metformin is similar to the sulphonylureas, in improving both fasting and post-prandial plasma glucose levels by approx. 25-30%. Metformin, unlike the sulphonylureas, does not promote insulin secretion and does not cause weight gain and is therefore preferable in obese NIDDM. Metformin is also of benefit as combined therapy with a sulphonylurea, and in older subjects the two drugs may give as good glycaemic control as insulin. Lactic acidosis with metformin is less common than sulphonylurea-induced hypoglycaemia although the mortality risk is similar. However, where both groups of drugs are properly used clinically, serious side-effects are unusual. Metformin may have a potential advantage in the management of NIDDM with hyperinsulinaemia in that it does not increase insulin levels. Where insulin levels have been compared in the same type II patients, metformin can achieve similar glycaemic control as a sulphonylurea (gliclazide) but with significantly lower plasma insulin levels.