This study examines the rate of decline of estimated glomerular filtration rate (eGFR) over a 10-year period and the associated risk factors in type 2 diabetes mellitus (T2DM) patients. Medical records of T2DM patients were randomly selected. The rate of fall in eGFR (simplified modification of diet in renal disease formula) was used as a measure of decline. Univariate and multivariate analysis were performed to determine the factors associated with decline of kidney function. A total of 504 patients were selected. Mean age was 57.8 ± 9 years; 65.3% were females. The mean decline rate of eGFR was 0.89 ± 2.16 mL/min/1.73 m²/y. Baseline proteinuria, glycosylated hemoglobin level, duration of T2DM, and Malay race were associated with faster decline in eGFR. The expected greater deterioration in kidney function in this cohort was not seen. Treatment of proteinuria and glycemia should be optimized early to retard the decline in kidney function in patients with T2DM.