Abstract： Objective To compare phenotype diversity between senile and middle age, newly diagnosed type 2 diabetic patients. Methods 416 newly diagnosed adults （aged 40 to 90 years） with type 2 diabetes were divided into two groups （senile group aged 60 to 90 vs middle age group aged 40 to 60 years）. BP, BMI, waist-hip ratio, fasting and postprandial blood glucose and insulin, HbA1c, albuminuria and plasma lipid profile were detected. Insulin sensitivity was determined by HOMA-IR, and β cell function was determined by HOMA-β. Insulin release index [（30 min Ins-0 min Ins）/ （30 min BG-0 min BG）] was calculated as a marker of early secretion. Results Compared with middle age group, the senile group had higher values of waist-hip ratio （0.93±0.07 vs 0.90±0.06, P<0.01）, systolic pressure （153.0±2.3 vs 134.0±2.8 mm Hg, P<0.05） and HOMA-IR （5.8±1.2 vs 5.5±1.2, P<0.05）. But the values of BMI （24.4±3.6 vs 25.1±2.9, P<0.01）, postprandial insulin secretion （61±33 vs 69±37 mU/L, P<0.05）, TC, TG, LDL, HDL, HOMA- β cell （89±49 vs 102±44, P<0.01） and △I30/△G30 （3.30±0.25 vs 4.71±0.19, P<0.01） were lower in the senile group vs in middle age group. Conclusion Compared with middle age group, the senile group has obvious insulin resistance and β-cell deterioration. Central obese, hypertension and microalbuminuria were the most important phenotype of insulin resistance in senile patients