THE EFFECT OF METABOLIC CONTROL ON RATE OF DECLINE IN RENAL-FUNCTION IN INSULIN-DEPENDENT DIABETES-MELLITUS WITH OVERT DIABETIC NEPHROPATHY

Background. Strict glycaemic control has been shown to reduce the risk of developing diabetic nephropathy. In established nephropathy, howev er, the impact of glycaemic control on prognosis is less clear. Theref ore we investigated the effect of long-term glycaemic control on the d ecline in renal function in insulin-dependent diabetic patients with o vert nephropathy. Methods. The study was performed at two hospital-bas ed diabetes centres in western Sweden. The study was an observational retrospective follow-up study in 158 insulin-dependent diabetics with proteinuria with a mean (+/-SD) age of 36+/-9 years and a diabetes dur ation of 22+/-8 years. The change in glomerular filtration rate was me asured as Cr-51 EDTA clearance for a median of 8 years (range 1-17). G lycaemic control was determined with measurements of glycated haemoglo bin A(1c). Results. The decline in glomerular filtration rate was 3.8/-3.7 ml/min/year. The blood pressure was 143/82+/-15/7 mmHg and the m ean glycated haemoglobin was 8.7+/-1.6%. The correlation coefficient b etween glycated haemoglobin and decline in glomerular filtration rate was -0.39 (P<0.0001) and between decline in glomerular filtration rate and systolic and diastolic blood pressure -0.17 (P=0.03) and -0.29 (P =0.003) respectively. In patients with glycated haemoglobin <8.0% and diastolic blood pressure <85 mmHg the decline in glomerular filtration rate was 1.7+/-2.3 ml/min/year. Conclusions. In this retrospective ob servational study, effective blood-pressure control was associated wit h a low rate of decline in renal function and a low urinary albumin ex cretion. The correlation between glycaemic control and decline in rena l function indicates that poor glycaemic control can accelerate the lo ss of renal function in diabetic nephropathy.