Development of renal structural lesions in type-1 diabetic patients with microalbuminuria

Abstract

Kidney biopsies were obtained in 18 type-1 diabetic patients with microalbuminuria and again 8 years later. Over the first 30 months, a treatment protocol (conventional versus intensified treatment) was followed. The biopsies were embedded into plastic and sectioned serially. The volume of individual glomeruli and the vascular pole area was determined. The number of glomeruli showing capsular drops, fibrinoid lesions, adhesions, extra efferent arterioles and corpuscles totally occluded were counted and expressed as a percentage of the total number of corpuscles. Cortical interstitium and degenerated tubules were estimated by point counting. From baseline to the 8-year biopsy, the group of patients showed significant increase in interstitial volume fraction, mean glomerular volume and vascular pole area. The frequency of glomerular occlusion, fibrinoid lesions, adherences and extra efferent arterioles increased, whereas the frequency of capsular drops did not change, and degenerated tubular profiles showed a non-significant increase. No correlation was seen between these light microscopic observations and the concomitant development of diabetic glomerulopathy. Increase in albumin excretion rate was associated with increase in glomerular volume and vascular pole area. No correlation was seen with the glomerular filtration rate, blood pressure or metabolic control. The increase in structural parameters illustrates the slowly ongoing alteration of renal structures in type-1 diabetic patients with microalbuminuria.