Insulin treatment of non-insulin-dependent diabetes mellitus

The standard treatment of NIDDM consists of diet, oral hypoglycaemic agents and, mostly as a last resort, insulin. Indications for insulin therapy cannot be generalized for the whole population of NIDDM patients. The defined objectives of therapy for the individual patient will determine the choice and intensity of therapy. These will usually be either a relief of hyperglycaemic symptoms in the elderly patient or normoglycaemia, as in the insulin-dependent diabetic patients, in order to prevent acute and chronic complications. Primary insulin treatment is advisable in patients with hyperglycaemic symptoms and fasting blood glucose levels above 15 mmol/l, as in these patients the major defect will be insulin deficiency rather than insulin resistance. The correction of long lasting hyperglycaemia partly restores insulin sensitivity and B cell function, thereby allowing sequential reduction of insulin dosage. When metabolic control can be sustained with low insulin dosages some of these patients may later respond well to oral hypoglycaemic agents or to diet alone. In the management of non-insulin-dependent diabetic patients it is of great importance to recognize in time when treatment with oral hypoglycaemic agents fails. Insulin therapy should not be withheld on the presumption that it will cause weight gain and will promote development of macrovascular disease. Weight gain can be reduced by adequate dietary counselling and the level of macrovascular risk factors reduces with improved metabolic control. In this context also it should be realized that the correction of hypertension, hyperlipidaemia and the cessation of cigarette smoking is probably of equal importance. Insulin therapy regimens which have been used in non-insulin-dependent diabetic patients have been the same as prescribed for insulin dependent patients. When considering the fact that hepatic overproduction of glucose is the major determinant of fasting blood glucose level and that postprandial glycaemic excursions are superimposed on this level it seems reasonable to aim for normalization of the basal hepatic glucose production. A bedtime injection of an intermediate or long acting insulin can be used for this aim. Other therapeutical approaches which have been studied recently are the use of combinations of insulin and oral hypoglycaemic agents and the use of proinsulin as an alternative for intermediate acting insulin. Before these forms of therapy can be advocated long-term clinical studies are necessary to define their therapeutic role.