Clinical and histologic predictors of non-diabetic kidney disease in patients with diabetes mellitus

INTRODUCTION: The number of kidney biopsies performed in patients with diabetes has increased rapidly over the last two decades. However, the overall value of the biopsy has been questioned because any coexisting non-diabetic kidney disease (NDKD) is not identified in many patients. Here, we quantify the frequency of identifying NDKD and examine clinical indications, demographic factors, and histologic parameters that increase the odds of finding NDKD and the impact on developing end stage kidney disease. METHODS: A retrospective analysis of clinical and pathologic parameters of 49,075 biopsied patients with diabetes with and without diabetic nephropathy (DN) from 2001-2024 was performed. Data from the United States Renal Data Service were examined to determine the impact of a NDKD on disease progression to end stage kidney disease. RESULTS: NDKD was found in 58.8% of patients with diabetes who underwent kidney biopsy, including 35.9% without concurrent DN and 22.9% as a second diagnosis in DN. Acute kidney injury and acute nephritic syndrome had greater odds of a NDKD diagnosis in patients with DN. The youngest (under 30 years) and oldest (60 years and older) patients had a higher prevalence of NDKD. Higher chronicity on biopsy was associated with a lower prevalence of NDKD diagnosis. Patients with NDKD were 2.56-fold less likely to develop end stage kidney disease compared to patients with DN alone. CONCLUSIONS: This is the largest analysis examining prevalence of a NDKD in patients with diabetes and the impact of biopsy indication on finding a second diagnosis in biopsy-proven DN. The objective is to provide nephrologists with guidance in when to perform a biopsy based on the odds of finding a NDKD related to the patient's clinical indication. Given the high prevalence of NDKD, our study shows that kidney biopsy remains a critical tool in the care of diabetic patients.