Predictors of the development of microalbuminuria in patients with Type 1 diabetes mellitus: a seven-year prospective study

Aims To determine risk factors for the development of persistent microalbum inuria (albumin excretion rate (AER) greater than or equal to 30 mu g/min) in Type 1 diabetes mellitus. Methods One hundred and forty-eight initially normotensive Type 1 diabetic patients with normal albumin excretion (<30 mu g/min) were followed prospec tively in hospital diabetes outpatient clinics for a median of 7 years, Mai n outcome measures were: progression to persistent microalbuminuria (albumi n excretion rate greater than or equal to 30 mu g/min on at least two conse cutive occasions); rate of change of albumin excretion rate; development of arterial hypertension (systolic blood pressure >160 mmHg and/or diastolic blood pressure > 95 mmHg or commencement of antihypertensive therapy). Results In a median follw-up period of 7 years (range 6 months to 8 years), 14 patients progressed to persistent microalbuminuria, a cumulative incide nce of 11% (95% confidence interval 6.36-16.94), AER remained persistently < 30 mu g/min in 109 subjects and 25 developed intermittent microalbuminuri a, In those who developed persistent microalbuminuria, baseline AER (16.2 ( 13.9-19.1) vs, 5.2 (3,8-9,2) mu g/min, P<0.01), blood pressure (136 (123-14 8)/80 (74-85) vs, 121 (118-124)/72 (70-73) mmHg, P < 0.05), and HbA(1) (10. 2 (9.1-11.4) vs, 9.0 (8.7-9.4)%, P < 0.05) were higher than in those who co ntinued to have persistent normoalbuminuria, retinopathy was more severe an d height (1.64 (1.57-1.71) vs, 1.70 (1.69-1.72) m, P < 0.05) less. In multi variate analysis, baseline AER was the strongest predictor of the developme nt of persistent microalbuminuria (P < 0.0001), followed by mean arterial p ressure (P = 0.02) and HbA(1) (P = 0.05). Conclusions The level of AER, raised blood pressure and poor glycaemic cont rol are the most important predictors of the development of microalbuminuri a in Type 1 diabetes.