Diabetes mellitus causes profound alterations in many body tissues. Microvascular diabetic complications include diabetic neuropathy, nephropathy and retinopathy. Nephropathy first becomes manifest with hyperfiltration and microalbuminuria. These functional changes evolve over several years to a stage of marked deterioration of renal function. The possible preventive measures are metabolic control, reduction of dietary protein intake and use of ACE-inhibitors. Metabolic control is also important for the prevention of diabetic retinopathy. In fact, patients with HbA1c higher than 10% have an increased risk of progression of retinopathy. Moreover, an accelerated progression of retinopathy has been observed in patients with systemic hypertension following the onset of microalbuminuria. It has been demonstrated that diabetic neuropathy can also be present during childhood; therefore, it is possible to detect electrophysiological abnormalities in children and adolescents with IDDM. Glycaemic and blood pressure control are, so far, the main means for possible prevention or modification of the natural history of diabetic microvascular complications. Tight glycaemic control may have beneficial effects for diabetic neuropathy. In addition, other preventive measures, such as aldose reductase inhibitors, gangliosides, neurotrophic vitamins, etc., have been studied in the last years. However, no conclusive results have been obtained so far.