[Microalbuminuria in diabetes mellitus--illness or symptom?]

Microalbuminuria (MA) is a term used for urinary albumin excretion between 20 and 200 micrograms/min. or 30-300 mg/24 h. This definition is not used by all authors. In addition, various methods may influence the results. The significance of MA concerns the prognosis in diabetics. For the juvenile type 1 diabetes nephropathy is the most important complication. In adult type 2 diabetics the prognosis concerns mainly cardiovascular death. The excess mortality to be attributed to MA is several fold in type 1 diabetes, less in the adult onset type variety. MA is the expression of an incipient general disease of blood vessels touching as much the kidney as the heart. According to the presence or absence of other vascular damage. MA develops toward nephropathy or cardiovascular complications. The features leading to or worsening MA are elevated blood pressure, poor glucose control, elevated lipoproteins, diminished insulin sensitivity and probably smoking. Retinopathy is an indicator for particularly sensitive patients responding with the development of MA upon only mildly elevated blood pressure or poor metabolic control. The prevalence of MA is close to 20% for both types of diabetes. Non-diabetic persons under 60 years of age exhibit MA in 2-10%, the elderly in 20-30%. For non-diabetic persons with hypertension MA is reported to be present in 19%. Over a time span of 5 years, 19% of type 1 patients with MA develop proteinuria of more than 300 mg/24 hours. In a third of cases albumin excretion normalises. In the remaining half a small progression of MA occurs. For type 2 patients the increased mortality risk is restricted to the first 5 years, thereafter the survival curves return to those of patients without MA. In these patients the excess mortality is already present at albumin excretion rates above 10 micrograms/min. Higher values have, therefore, to be considered pathological. For the treatment of the syndrome ACE-inhibitors and ev. Ca-antagonists (with the exception of dihydropyridine, nifedipine) are recommended. They reduce albumin excretion by 50%. In a single study (yet) with type 1 diabetes mortality also was reduced by 40-50%. This would imply that the excess mortality could be halved in patients undergoing this treatment.