Lack of association between cystopathy and progression of diabetic nephropathy in insulin-dependent diabetes mellitus

Whether an association exists between cystopathy and progression of diabetic nephropathy has never been clarified. The aim of the present study was to measure the degree of cystopathy in relation to the rate of progression of diabetic nephropathy. To that end, 17 insulin-dependent diabetic patients with diabetic nephropathy but without voiding symptoms were investigated urodynamically. The median age of the patients was 45 years (range 27-67 years), diabetes duration 23 years (range 14-44 years) and the serum creatinine level was 162 mumol/L (median, range 65-449 mumol/L) at the time of the study. The progression rate of diabetic nephropathy was analysed retrospectively by measuring changes in yearly mean values of Log10 serum creatinine for a period of 13 years (3-15 years) before the investigation. The progression rate was 0.028 mumol/L/year (median). Patients with a progression rate above and below the median rate were considered to be rapid (n = 8) and slow (n = 9) progressors, respectively. More women than men had a rapid progression rate of nephropathy. Rapid progressors were found to have smaller volume or residual urine (90 vs 165 ml; p < 0.05), larger volume voided (440 vs 270 ml; p < 0.05), lower opening pressure (18 vs 48 cm H2O; p < 0.05) and lower pressure at maximum flow (37 vs 64 cm H2O; p < 0.05) compared to slow progressors. However, these variables were not related to the progression rate of nephropathy (MANOVA). Furthermore, these results should be interpreted with caution because of the natural gender differences in pressure conditions. In conclusion, rapid progression of diabetic nephropathy does not seem to be associated with dysfunction of the urinary bladder measured with cystometry and pressure flow.