OBJECTIVE To investigate the course of microalbuminuria during the 1980s in type I diabetes patients.

RESEARCH DESIGN AND METHODS This was a 10-year follow-up of 109 patients in whom type I diabetes was diagnosed between 1961 and 1980 before 15 years of age and who were initially investigated between 1977 and 1983 after a diabetes duration of ≥ 3 years. Microalbuminuria was defined as an albumin excretion rate (AER) of 20-200 μg/min in two of three consecutive urine samples.

RESULTS At the initial investigation, 81 patients had normal AER, 27 had microalbuminuria, and 1 had macroalbuminuria. Between 1989 and 1992, 99 (91%) patients were reinvestigated. Only 5 (19%) of the initially microalbuminuric patients developed macroproteinuria during the 10-year follow-up period, and in 15 (58%) patients, AER decreased to normal. Three (4%) of the normoalbuminuric patients developed microalbuminuria but none macroproteinuria. The initially microalbuminuric patients, in whom AER normalized, improved their glycemic control from 1980-1983 to 1989-1991 (mean ± SE HbA_1c 7.5 ± 0.2 to 6.6 ± 0.3%; P = 0.01).

CONCLUSIONS In the majority of patients with microalbuminuria in whom it is possible to obtain good glycemic control, microalbuminuria will disappear and the risk of developing nephropathy will be markedly reduced.