THE DETERMINANTS OF EARLY NEPHROPATHY IN INSULIN-DEPENDENT DIABETES-MELLITUS - A PROSPECTIVE-STUDY BASED ON THE URINARY-EXCRETION OF ALBUMIN

A four-year prospective study of the factors predicting albuminuria was carried out in 172 normotensive, insulin-dependent diabetic patients without overt nephropathy. Urinary albumin excretion was estimated as the urinary albumin:creatinine ratio (U(A)/U(C)) in an early morning sample. Multivariate analysis showed that U(A)/U(C) on the return visit was positively associated with the U(A)/U(C) (p < 0.001) and glycosylated haemoglobin (HbA1; p < 0.001) at initial examination; weaker associations were found with a history of hospital admission (p < 0.05) and smoking (p < 0.05), and with treatment of blood pressure (p < 0.05). Neither initial blood pressure, heart rate, nor creatinine clearance were significant predictors of the U(A)/U(C). Two patients died from coronary heart disease, both of whom had raised albumin excretion at initial examination. Eleven (6.8 per cent) of the 160 patients who were studied repeatedly developed macroalbuminuria (U(A)/U(C) > 45.5 mg/mmol): they had a significantly higher initial U(A)/U(C) (p < 0.005), HbA1 (p < 0.05) and a greater frequency of retinopathy (p < 0.05) than patients matched for age, sex and duration of diabetes who did not develop macroalbuminuria. Simultaneous measurements of the U(A)/U(C) and HbA1 should be used when screening for microalbuminuria in diabetets mellitus: patients with a high U(A)/U(C) (e.g. > 3.5 mg/mmol) and HbA1 (e.g. > 13 per cent) should be closely monitored even when blood pressure is normal.