[Screening of subjects at high risk for diabetic microangiopathies]

Chronic hyperglycemia is the single most important pathogenic factor in the diabetic triad: retinopathy, glomerulopathy and neuropathy. But at equal serum glucose balance, diabetics are not equally at risk of microangiopathy. Hence the importance of timely screening of patients who should be convinced to accept the constraints and risk of perfect serum glucose balance or to whom specific therapy independent from serum glucose balance could be proposed. But at present, there is no genetic or immunologic marker allowing for the individual identification of at risk patients. Attention is thus directed towards factors which may be directly involved in the pathogenesis of diabetic microangiopathy: --Special sensitivity of vascular collagen to protein glycosylation which could be reflected in the involvement of tendon and aponeurotic collagen, --platelet abnormalities of which the exacerbating role appears to be confirmed by the significant efficacy of aspirin in the treatment of nonproliferative retinopathy in insulin-independent diabetics, --rheological abnormalities which might essentially be secondary to chronic hyperglycemia, --hormonal abnormalities, in particular hypersecretion of growth hormone and/or somatomedin C, whose role has long been suspected and could be established by therapeutic trials with new somatostatin analogues. But the most recent advances concern the study of hemodynamic factors. Irreversible organic diabetic microangiopathy is thought to be preceded by a phase of reversible functional microangiopathy, characterized by increased capillary blood flow, vascular dilatation, hyperpermeability and altered regulation of flow. Thus, diabetic glomerulopathy with decreased glomerular filtration is preceded by a phase of renal "hyperfunctioning" and irreversible proteinuria is the outcome of a progressive increase in microalbuminuria, reversible at least while the levels are not too high.(ABSTRACT TRUNCATED AT 250 WORDS)