Diabetic nephropathy (DN) may be more prevalent than previously appreciated, according to a new autopsy study.

Celine Q.F. Klessens, MD, and colleagues at Leiden University Medical Center in Leiden, The Netherlands, retrospectively collected and analyzed renal tissue specimens from autopsies and clinical data from 168 patients with diabetes. The cohort included 17 patients with type 1 diabetes, 127 with type 2 diabetes, and 24 whose diabetes type was unclear. The researchers found histologically proven DN in 106 patients (63%), of whom 20 did not present with DN-associated clinical manifestations within their lifetime, the investigators reported online ahead of print in Kidney International. “This may indicate that renal lesions consistent with DN may develop before the onset of clinical abnormalities,” the authors wrote.

According to previous studies, the prevalence of clinically diagnosed DN among patients with type 1 diabetes ranges from 5% to 20% and its prevalence in patients with type 2 diabetes ranges from 25% to 35% based on microalbuminuria or proteinuria findings, Dr. Klessens’ group stated. They pointed out that data on renal pathologic conditions in patients with DN is relatively limited because renal biopsies are only performed in cases in which the manifestations of renal disease cannot be explained sufficiently by the presence of clinically suspected DN. Relatively few studies of DN have confirmed clinical manifestations of the disease by renal biopsy, they noted.

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With respect to the distribution of DN classes, 22 cases were class 1, 33 were class II, 45 were class III, and 6 were class IV.

The investigators noted that they had the benefit of being able to study at least 100 glomeruli per patient, approximately 10-fold more glomeruli than usually is available in a renal biopsy sample. “Given the large amount of tissue available, we were not only certain about the presence or absence of DN, but when DN was present, we were also certain of its distribution over the 4 classes and the severity of interstitial lesions.”

The authors stated that the potential clinical benefit of identifying patients with undiagnosed DN remains unclear. “For example, the ability to diagnose DN in an early state might enable clinicians to begin a specific therapeutic regimen that could slow disease progression and may ultimately prevent the onset of end-stage renal disease,” they wrote.