Kidney Pathology in Diabetes: A Comparative Study of Youth and Young Adults

Rates of progression to kidney failure have been shown to differ by age of diabetes diagnosis in many populations. We evaluated clinically performed kidney biopsies to better understand this observation. We hypothesized that youth with a diabetes diagnosis have more nondiabetic kidney pathology than young adults.

This retrospective cohort study used a kidney biopsy registry linked to the Manitoba Centre for Health Policy (MCHP) to evaluate all kidney biopsies (2002 to 2021) from young adults (19 to 40 years of age) with a diagnosis of diabetes. Kidney biopsies of youth (≤18 years) and additional adult biopsies from the 2022-2023 period were manually reviewed. Clinical data were extracted from MCHP (young adults) and clinical charts (youth), including sex, age, diabetes duration, glycated hemoglobin (A1C), estimated glomerular filtration rate (eGFR), urine albumin:creatinine ratio (ACR), hypertension status, and medications.

One hundred fifty-three young adult and 34 youth biopsies were included in the study. Diabetes duration at time of biopsy was a median of 5.0 (1.0 to 10.0) years for young adults and 2.8 (1.3 to 4.9) years for youth. Young adults had lower A1C (7.6% vs 10.3%, p<0.0001), more albuminuria (median ACR 330.0 [172.3 to 591.5] vs 94.0 [34.9 to 204.8] mg/mmol, p<0.0001), and lower eGFR (37 vs 143 mL/min per 1.73 m², p<0.0001) at time of biopsy. Youth had more nondiabetic kidney pathology compared with diabetic pathology in young adults, including nonproliferative glomerulonephritis (29.4% vs 13.7%, p=0.05). Young adults had more severe tubulointerstitial scarring (52.2% vs 5.9%, p<0.0001).

Youth with diabetes are more likely to have nondiabetic kidney diseases, whereas adult biopsies demonstrated more severe diabetic nephropathy and chronic scarring. Further research is needed to explore associations between clinicopathologic changes and eGFR trajectories.