ROLE OF GLYCEMIC CONTROL IN DEVELOPMENT OF MICROALBUMINURIA IN PATIENTS WITH INSULIN-DEPENDENT DIABETES

Objective-To ascertain which factors determine the progression from ve ry low rates of albumin excretion to persistent microalbuminuria in pa tients with insulin dependent diabetes mellitus. Design-A 10 year pros pective study of a cohort of diabetic patients. Setting-Outpatient dep artment of the Portsmouth District Hospitals. Subjects-97 patients wit h insulin dependent diabetes mellitus who were initially free of micro albuminuria and hypertension. Main outcome measure-Urinary albumin: cr eatinine ratio. Results-Eight of the 97 patients had developed microal buminuria (urinary albumin:creatinine ratio >3 mg/mmol in three consec utive early morning samples) by the 10 year follow up. The group who d eveloped microalbuminuria had higher baseline log(10) plasma glucose c oncentrations (mean (SD), 1.210 (0.122) v 0.984 (0.196) mmol/l, P < 0. 001) and glycated haemoglobin concentrations (1.112% (0.069%) v 0.997% (0.076%), P < 0.001) and a younger age at onset of diabetes (10.0 (5. 5) v 15.6 (7.8) years, P < 0.05). There was no difference in baseline duration of diabetes, smoking, sex, insulin dose, body mass index, ser um creatinine concentration, or systolic, diastolic, or mean arterial blood pressure between the two groups. Multiple linear regression anal ysis showed that urinary albumin:creatinine ratio at 10 years was infl uenced by initial albumin: creatinine ratio (P = 0.006), initial glyca ted haemoglobin concentration (P = 0.002), and duration of diabetes (P = 0.045). Genotype for angiotensin converting enzyme was not related to the development of microalbuminuria nor, in a larger group of patie nts, the presence of any degree of diabetic nephropathy. Conclusion-In patients with insulin dependent diabetes mellitus the progression of minimal albuminuria and the development of microalbuminuria is determi ned primarily by poor long term glycaemic control. There is a weaker r elation with longer duration of disease and younger age at onset of di abetes, but blood pressure does not seem to be implicated. Gene polymo rphism for angiotensin converting enzyme is not linked to the developm ent of microalbuminuria or established diabetic nephropathy.