Long‐term studies of the juxtaglomerular apparatus in young microalbuminuric type 1 diabetic patients

Aim: To determine the long-term changes of the juxtaglomerular apparatus in incipient diabetic nephropathy. Methods: Three renal needle biopsies were performed on 15 young type 1 diabetic patients with microalbuminuria; at baseline and after an average of 2.4 and 8.2 years. Using light microscopy, 1 μm serial sections of the plastic-embedded biopsies were investigated and volumes of the juxtaglomerular apparatus and glomerulus and areas of the macula densa and lumina of the afferent and efferent arterioles were measured. Results: From baseline to second follow-up there was a significant decrease in JGA relative to glomerular volume. There was an increase in luminal area of the efferent arteriole which was paralleled by (non-significant) changes in the afferent arteriole. Conclusion: Over a period of 8.2 years JGA size remained stable, but decreased relative to glomerular size. Also, an increase in luminal area was noted in efferent arterioles. This may be due to increased single nephron blood flow secondary to nephron loss.