Structural Lesions on Kidney Biopsy in Youth-Onset and Adult-Onset Type 2 Diabetes

Objective: Type 2 diabetes (T2D) is a leading cause of end stage kidney disease (ESKD) worldwide. Recent studies suggest a more aggressive clinical course of diabetic kidney disease (DKD) in youth-onset than adult-onset T2D. We compared kidney structural lesions in youth- and adult-onset T2D to determine if youth-onset was associated with greater early tissue injury.

Methods: Quantitative microscopy was performed on kidney tissue obtained from research kidney biopsies in 161 Pima Indians (117 women, 44 men) with T2D. Onset of T2D was established by serial oral glucose tolerance testing and participants were stratified as youth-onset (<25 years) or adult-onset (≥25 years). Associations between clinical and morphometric parameters and age of onset were tested using linear models.

Results: At biopsy, the 52 participants with youth-onset T2D were younger than the 109 with adult-onset T2D (39.1±9.9 vs. 51.4±10.2 years, p<0.0001), but their diabetes duration was similar (19.3±8.1 vs. 17.0±7.8 years, p=0.09). Median urine albumin-to-creatinine ratio was higher in the youth-onset group (58 [25^th-75^th percentile, 17-470] vs. 27 [13-73] mg/g, p=0.02). Youth-onset participants had greater glomerular basement membrane (GBM) width (552±128 nm vs. 490±114nm, p=0.002) and mesangial fractional volume (0.31±0.10 vs. 0.27±0.08, p=0.001) than adult-onset participants. Percentage glomerular sclerosis, glomerular volume, mesangial fractional volume, and GBM width were also inversely associated with age of diabetes onset as a continuous variable.

Conclusion: Younger age of T2D onset strongly associates with more severe kidney structural lesions. Studies are underway to elucidate the pathways underlying these associations.