Background: Obesity has been linked to chronic kidney disease (CKD) in the general population, but little is known about the association of obesity and changes in obesity status with CKD in the diabetic population.
Methods: A cohort of 1199 Taiwanese adults with type 2 diabetes was followed up from baseline (2003-2005) to 2010. We evaluated BMI at baseline and repeated in 2008, 2009, and 2010 as a continuous term and a category according to the World Health Organisation (WHO) cut-off points for Asian populations (normal: <23; overweight: 23.0-27.4; obese: ≥27.5 kg/m2). Relative changes in BMI between baseline and 2010 were evaluated as a continuous variable in percentage (%) and a category (<-5, ±5, >+5 to +10, and >+10%). CKD was defined as estimated glomerular filtration rate (eGFR) <60 mL/min/1.73m2 in each time point. We used generalized estimating equation models for repeated measure BMI and CKD, and logistic regression models for changes in BMI and CKD outcomes in 2010.
Results: At baseline, 49.4% of subjects were overweight and 29.6% were obese. After a 7-year follow-up, the overall prevalence remained similar in 2010, but over 40% of subjects had a BMI change greater than ±5%. We found higher BMI levels (OR=1.05, p=0.018) and greater changes in BMI (OR=1.06, p<0.001) to be positively associated with CKD. The multivariate-adjusted OR for CKD was 1.33 (95% CI=0.95-1.86, p=0.102) for overweight category and 1.67 (95% CI=1.11-2.51, p=0.013) for obese category compared with normal BMI category. Subjects who had a BMI increase >10% had a significant increased risk for CKD (OR=2.79, 95% CI=1.49-5.21, p=0.001) compared with those who remained within a ±5% range of their baseline BMI.
Conclusions: In this large cohort of type 2 diabetes, patients who had a high BMI or gained weight over a 7-years follow-up period had a significant increased risk of CKD.