China is stepping into the aging society. The prevalence of type 2 diabetes among elderly population is increasing in China in the last few decades. However, there is a lack of epidemiological investigations regarding to the aging-related changes of islet function in the elderly population. To investigate the islet function and glycemic conditions in the elderly population of western China. Using a complex, multistage, probability sampling design, we conducted a cross-sectional survey in a provincial representative sample of 3001 western Chinese elderly adults. A 2 h oral glucose tolerance test (OGTT) was conducted among all study participants, and islet function measurements including HOMA-β, HOMA-IR, HOMA-IS, ΔI30/ΔG30, Ip/I0 were calculated. HOMA-β, HOMA-IR and ΔI30/ΔG30 decreased gradually along with increasing age from age of 55 to age of 80 (p <0.05). HOMA-IR, HOMA-β and ΔI30/ΔG30 were significantly higher while HOMA-IS lower among urban residents than rural residents or suburb residents (p <0.01). FPG, 2 h plasma glucose (P2hPG) and HbA1C increased with increasing age (p <0.05), while fasting insulin level (FINS) and 2 h insulin level (P2hINS) decreased with increasing age (p <0.05). FPG, P2hPG and glycated hemoglobin (HbA1C) among suburb residents were lower than among urban residents and among rural residents (p <0.05). Islet function decreased gradually along with increasing age with no gender difference among the elderly population in western China. Glycemic outcomes became worse with increasing age. These results indicated that strategies aimed at the prevention of diabetes in the elderly population were needed.