Objective To explore the characteristics and risk factors of type 2 diabetes mellitus (T2DM) onset in pedigrees. Methods A total of 865 subjects were screened and diagnosed by oral glucose tolerance test (OGTT) based on American Diabetes Association (ADA) criteria. Type 1 diabetes mellitus (T1DM) , maturity onset diabetes of the young (MODY) and chondriosome diabetes were excluded by clinical features and laboratory test of insulin and autoantibodies including glutamic acid decarboxylase antibody, insular cellular antibody and insulin autoantibody. A total of 182 pedigrees of T2DM were obtained. Results No gender difference was found in the prevalence of T2DM (42. 59% in male and 48. 18% in female respectively, P ＞0. 05) , nor was the newly diagnosed rate(9. 89% in male and 11. 82%in female, P ＞ 0. 05). The onset age was (63. 3 ± 12. 4) years old in the first generation [(64. 4 ± 12. 5)years in male and (62. 3 ± 10. 3) years in female] , (47. 1 ± 8. 7) years old in the second generation [(48. 2 ±9. 3)years in male and (46. 1 ± 8. 1) years in female] , (29. 6 ± 10. 2) years old in the third generation [(28. 9 ±9. 5)years in male and (30. 0 ± 10. 4)years in female]. Compared with normal glucose tolerance (NGT) subjects , newly diagnosed T2DM and impaired glucose regulation (IGR) subjects had higher prevalence of hypertension, hyperlipidemia and smoking but less physical activities. Statistical differences were shown in body weight five years before diagnosis, one years before diagnosis and at diagnosis in newly diagnosed T2DM[(68. 4 ±12. 4)kg, (69. 5 ± 11. 0)kg and (69. 1 ±9. 6)kg] and IGR[(66. 1 ±10.7)kg, (65.9 ± 10.7) kg and(65.7 ± 10.4) kg] , when compared with NGT [(61.0 ± 10.2) kg,(59. 5 ±11.0) kg and (60. 1 ± 10. 4) kg, all P ＜ 0. 05] . The same results were obtained with waist circumference and waist-hip ratio [(4. 1 ± 12. 5) cm and 0. 92 ± 0. 36 in newly diagnosed T2DM while (89. 1 ± 10. 7) cm and 0. 90 ± 0. 64 in IGR] , when compared with NGT[(82. 5 ± 10. 1) cm and 0. 82 ±0. 25] , all P ＜0. 05. Conclusions No gender difference was found in the onset characteristics of T2DM.High prevalence of obesity, hypertension, hyperlipidemia and smoking with less physical activities were associated with T2DM.