Age-related differences in renal function decline and associated factors in type 2 diabetes mellitus: A prospective cohort study

Aims To compare estimated glomerular filtration rate (eGFR) trajectories between older and non-older adults with type 2 diabetes mellitus and to identify factors associated with eGFR decline in each group. Methods In this 5-year prospective cohort, 251 adults were classified as older (≥65 years) or non-older (<65 years). eGFR slopes were estimated with linear mixed-effects models, and factors associated with 5-year eGFR change were examined with multivariable linear regression. Results Older adults had a lower baseline eGFR but a slower decline in the main model (−1.715 vs −2.320 mL/min/1.73 m 2 /year; P = 0.030). The age-group difference was attenuated after separately accounting for baseline renin–angiotensin system inhibitor use ( P = 0.079) and for diabetes duration, body mass index, smoking, and hypertension ( P = 0.193). In older adults, higher systolic blood pressure and lower serum albumin were associated with greater eGFR decline; in non-older adults, higher low-density lipoprotein cholesterol, lower hemoglobin, and macroalbuminuria showed similar associations. Age-group interactions for these factors were not statistically significant. Conclusions Older adults exhibited a slower eGFR decline in the main analysis, but this difference was attenuated after accounting for renin–angiotensin system inhibitor use and baseline characteristics. Age-stratified associations require validation in larger cohorts.