Type 2 diabetes mellitus. Aspects of complications and treatment

Non-insulin-dependent or type 2 diabetes is a heterogeneous disorder, characterized by defects in insulin secretion as well as in insulin action; these defects are worsened by the developing hyperglycaemia. Diabetes is an independent risk factor for the development of cardiovascular disease. In addition to hypertension, which is encountered in almost 50% of patients, lipid abnormalities, comprising elevations of both LDL-cholesterol and VLDL-triglycerides, as well as decreases in the levels of HDL-cholesterol, contribute to the high prevalence of vascular disease. Elevated levels of serum lipoprotein(a) may add to this increased risk. Considering the apparent clustering of risk factors such as poor metabolic control, obesity, hypertension and dyslipidaemia, the attainment of optimal blood glucose control forms only one of the aims of treatment to prevent the neurological and vascular complications, which severely affect the quality of life. Dietary advice comprises the adoption of healthy eating habits and reducing the intake of refined sugars and saturated fat. The long-term metabolic effects of intensive dietary therapy, however, have been disappointing. This necessitates early pharmacological treatment in a considerable number of patients. With mild hyperglycaemia, the metabolic effects of sulphonylurea and insulin treatment were comparable, but insulin is superior to sulphonylurea in patients who are more hyperglycaemic (fasting blood glucose > 11 mmol/l). In addition to its effects on blood glucose control, insulin therapy favourably affects dyslipidaemia. Treatment can be safely instituted on an outpatient basis, and hypoglycaemic side-effects are infrequent. Combination therapy of insulin and sulphonylurea results in similar metabolic improvement when compared with insulin treatment alone, but with a lower dose of insulin and the need for only one injection in two-thirds of patients. Drugs such as ACE inhibitors, which have no metabolic side-effects, have become the therapy of choice when treating hypertension in diabetic patients.