Abstract

AIMS:

To determine risk factors for the development of persistent microalbuminuria (albumin excretion rate (AER) > or =30 microg/min) in Type 1 diabetes mellitus.

METHODS:

One hundred and forty-eight initially normotensive Type 1 diabetic patients with normal albumin excretion (<30 microg/min) were followed prospectively in hospital diabetes outpatient clinics for a median of 7 years. Main outcome measures were: progression to persistent microalbuminuria (albumin excretion rate > or =30 microg/min on at least two consecutive occasions); rate of change of albumin excretion rate; development of arterial hypertension (systolic blood pressure >160 mm Hg and/or diastolic blood pressure >95 mm Hg or commencement of antihypertensive therapy).

RESULTS:

In a median follow-up period of 7 years (range 6 months to 8 years), 14 patients progressed to persistent microalbuminuria, a cumulative incidence of 11% (95% confidence interval 6.36-16.94). AER remained persistently <30 microg/min in 109 subjects and 25 developed intermittent microalbuminuria. In those who developed persistent microalbuminuria, baseline AER (16.2 (13.9-19.1) vs. 5.2 (3.8-9.2)microg/min, P<0.01), blood pressure (136 (123-148)/80 (74-85) vs. 121 (118-124)/72 (70-73) mm Hg, P<0.05), and HbA1 (10.2 (9.1-11.4) vs. 9.0 (8.7-9.4)%, P<0.05) were higher than in those who continued to have persistent normoalbuminuria, retinopathy was more severe and height (1.64 (1.57-1.71) vs. 1.70 (1.69-1.72) m, P<0.05) less. In multivariate analysis, baseline AER was the strongest predictor of the development of persistent microalbuminuria (P<0.0001), followed by mean arterial pressure (P = 0.02) and HbA (P = 0.05).

CONCLUSIONS:

The level of AER, raised blood pressure and poor glycaemic control are the most important predictors of the development of microalbuminuria in Type 1 diabetes.