Background: Diabetic nephropathy is associated with renal structural changes involving all of the compartments. Most characteristic is the diabetic glomerulopathy. Studies of the histological changes during the early phases of nephropathy have included the glomerulopathy and also the juxtaglomerular structures. Neovascularization, well-known in diabetic retinopathy, has also been observed in the kidney. The present study concerns estimates of frequency of neovascularization at the vascular pole region in early stages of diabetic nephropathy.
Methods: Extra efferent arterioles at the glomerular vascular pole were detected during measurements of the vascular pole area applying 1-microm serial sections through kidney biopsies. It was observed that more than one efferent arteriole existed occasionally. The present study was carried out with the aim of estimating the frequency of this phenomenon in diabetic patients and in non-diabetic controls, the diabetic patients categorized according to the level of albumin excretion rate.
Results: Neovascularization was first observed in IDDM patients with microalbuminuria. Some of the cases presented the phenomenon in all of the glomeruli studied. As the examinations of many kidney biopsies continued the phenomenon was observed also in the non-diabetic control group and in one IDDM patient with normoalbuminuria. However, the frequency was statistically highly significantly increased in patients with elevated albumin-excretion. Within this group a strong correlation between frequency of neovascularization and the severity of diabetic glomerulopathy is seen.
Conclusions: The vascular abnormality localized to the vascular pole region is observed occasionally in the normal kidney, but the frequency is increased in patients with diabetic glomerulopathy. The abnormality may develop as a consequence of a long-standing diabetic glomerulopathy and might lead to less pronounced elevation of albumin excretion.