Abstract

Objective: Reduced nephron number is hypothesized to be a risk factor for chronic kidney disease and hypertension. Whether reduced nephron number accelerates the early stages of diabetic nephropathy is unknown. This study asked whether the rate of development of diabetic nephropathy lesions was different in type 1 diabetic (T1DM) patients with a single (transplanted) kidney compared to patients with two (native) kidneys.

Research Design and Methods: Three groups of volunteers were studied: 28 T1DM kidney transplant recipients with 8-20 years of good graft function, 39 two-kidney patients with duration of T1DM matched to the time since transplant in the one-kidney group, and 30 age-matched normal controls. Electron microscopic morphometry was used to estimate glomerular structural parameters on 3.0± 1.4 glomeruli per biopsy.

Results: Higher in the one vs. two-kidney diabetic groups, respectively, were serum creatinine (1.3± 0.4 vs. 0.9± 0.2 mg/dl, p< 0.001), systolic blood pressure (133± 13 vs. 122± 11 mmHg, p< 0.001) and albumin excretion rate [32.1(2-622) vs. 6.8(2-1,495) μg/min, p=0.006]. There were no differences in the one vs. two-kidney diabetic groups, respectively, in glomerular basement membrane width [511(308-745) vs. 473(331-814) nm], mesangial fractional volume (0.30± 0.06 vs. 0.27± 0.07), mesangial matrix fractional volume (0.16± 0.05 vs. 0.16± 0.06), and mesangial matrix fractional volume per total mesangium (0.16± 0.07 vs. 0.64± 0.09). However, these glomerular structural parameters were statistically significant higher in both diabetic groups compared to normal controls. Results were similar when patients receiving angiotensin-converting enzyme inhibitors were excluded from the analyses.

Conclusions: Reduced nephron number is not associated with accelerated development of diabetic glomerulopathy lesions in T1DM patients.