Diabetes, stone composition, and renal function in a large cohort of patients with nephrolithiasis

Nephrolithiasis is linked to chronic kidney disease (CKD), and diabetic patients may be at higher risk for renal decline. However, the interaction of diabetes, stone composition, and estimated glomerular filtration rate (eGFR) trajectory in patients with nephrolithiasis remains underexplored, particularly in community-based populations.

In this retrospective cohort study of adult stone formers with a urinary stone composition analysis on file, diabetes status and stone composition were extracted from electronic records of a large health maintenance organization. Longitudinal eGFR measurements assessed renal function decline, and the effects of stone type, diabetes, and recurrent stone events on eGFR trajectory were evaluated.

This study included 6,771 stone formers; 1,543 (23%) had diabetes. Diabetic patients had a significantly higher prevalence of uric-acid stones (18.3% vs. 6.5%, p<0.0001). Baseline eGFR differed robustly by stone type and diabetes status. After adjustment for age, sex, BMI, and hypertension, the rate of eGFR decline did not differ significantly by diabetes status within either the calcium-oxalate nor uric-acid subtype. Recurrent stone formers had greater renal function loss, while socioeconomic status had limited impact on eGFR change.

Diabetic and non-diabetic stone formers show distinct baseline eGFR profiles that differ by stone composition, and diabetes was strongly associated with uric-acid stone formation; however, diabetes was not associated with an accelerated rate of eGFR decline once adjusted for age, sex, BMI, and hypertension. These findings support baseline risk stratification, rather than an accelerated-decline phenotype, as the key actionable insight for diabetic stone formers.