Impact of Body Mass Index Variability on Kidney Disease Progression in a Large Type 1 Diabetes Cohort

Body mass index (BMI) variability an index of 'metabolic cycling' predicts kidney disease in type 2 diabetes, but studies in people with type 1 diabetes (pwT1DM) are scarce. We examined the relationship between BMI variability and diabetic kidney disease (DKD) progression in an ethnically diverse cohort of pwT1DM.

We analysed 3270 pwT1DM (52% female, 80% white) with baseline eGFR ≥ 45 mL/min/1.73 m² and ≥ 6 BMI measurements, attending two university hospital clinics (between 2004 and 2018). BMI variability was assessed using standard deviation (SD), visit-adjusted SD, variability independent of the mean (VIM), and average real variability (ARV). The primary endpoint was ≥ 50% eGFR decline with final eGFR < 30 mL/min/1.73 m². Multivariable and competing risk analyses (with mortality as competing risk) were performed.

Over a median of 9.6 years, 179 (5.5%) people reached the primary endpoint. Those who reached the primary endpoint had higher BMI variability, with baseline higher age, HbA1c, systolic blood pressure, albuminuria levels, and were more often of African-Carribean ethnicity as compared to those who did not. In multivariable models and competing risk analyses, all BMI variability indices were independent risk-factors for the primary endpoint. Visit-adjusted SD (HR 2.43, 95% CI 1.93-3.05) and ARV (HR 1.7, 95% CI 1.44-2.01) were the strongest BMI variability indices associated with the primary endpoint.

BMI variability is an independent predictor of DKD progression in pwT1DM. Further studies are required to elucidate the underlying mechanisms of our observations and explore if addressing BMI variability can translate to clinical benefits in DKD.