AIM: To assess the prospective association between objectively measured physical activity and kidney function over 4 years in people with Type 2 diabetes. METHODS: Individuals (120 women and 206 men) participating in the ADDITION-Plus trial underwent assessment of sedentary time (SED-time), time spent in moderate-to-vigorous-intensity physical activity (MVPA) and total physical activity energy expenditure (PAEE) using a combined heart rate and movement sensor, and kidney function [estimated glomerular filtration rate (eGFR), serum creatinine and urine albumin-to-creatinine ratio (ACR)] at baseline and after 4 years of follow-up. Multivariate regression was used to quantify the association between change in SED-time, MVPA and PAEE and kidney measures at four-year follow-up, adjusting for change in current smoking status, waist circumference, HbA1c , systolic blood pressure, triglycerides and medication usage. RESULTS: Over 4 years, there was a decline in eGFR values from 87.3 to 81.7 ml/min/1.73m(2) (P < 0.001); the prevalence of reduced eGFR (eGFR < 60 ml/min/1.73m(2) ) increased from 6.1 to 13.2% (P < 0.001). There were small increases in serum creatinine (median: 81-84 μmol/l, P < 0.001) and urine ACR (median: 0.9-1.0 mg/mmol, P = 0.005). Increases in SED-time were associated with increases in serum creatinine after adjustment for MVPA and cardiovascular risk factors (β = 0.013, 95% CI: 0.001, 0.03). Conversely, increases in PAEE were associated with reductions in serum creatinine (β = -0.001, 95% CI: -0.003, -0.0001). CONCLUSION: Reducing time spent sedentary and increasing overall physical activity may offer intervention opportunities to improve kidney function among individuals with diabetes. (Trial Registry no. ISRCTN 99175498).