Diabetic nephropathy: how effective is treatment in clinical practice?

Background: Diabetic nephropathy is the most common cause of end-stage renal failure in patients starting dialysis in the developed world. In clinical trials, interventions, particularly blood pressure control, have achieved major reductions in the rate of decline in renal function.
Aim: To investigate whether results from clinical trials can be achieved in routine clinical practice.
Design: Observational study of 170 consecutive patients referred to a combined diabetic-renal clinic over a 10 year period.
Methods: We collected demographic and laboratory data from the electronic patient record.
Results: Median serum creatinine at referral was 170 μmol/l and was >350 μmol/l in 26% of patients. Mean blood pressure (BP) was 159/85. The publication of guidelines by the Scottish Intercollegiate Guidelines Network in 1997, recommending more active intervention and earlier referral, had no impact on referral BP and creatinine. In the 125 patients with at least 1 year follow-up, significant improvements in BP, albuminuria, HbA_1c and serum cholesterol were seen. In the 63 patients followed up for 3 years (median creatinine 120 μmol/l), the median rate of decline in renal function slowed from 0.52 ml/min/month (first year) to 0.27 ml/min/month (third year) (p=0.003), nearly doubling the time to end-stage renal failure.
Discussion: Patients referred early to a combined diabetic-renal clinic benefited by slowing in the rate of decline of renal function. A challenging but achievable standard for audit would be to reduce the rate of progression to <0.25 ml/min/month in 70% of patients with diabetic nephropathy presenting with a serum creatinine <150 μmol/l.