Tanzania Journal of Agricultural Sciences 2015, Vol. 14(2) : 90-100Type 2 diabetes mellitus (T2DM) prevalence is increasing at alarming rates posing significant health problem in Tanzania. Urbanization with economic advancement has led to lifestyle behaviors such as high intake of dense caloric foods, sedentary lifestyle, smoking, and limited intake of fruits and vegetables. All these have been associated with higher prevalence of cardiovascular diseases, hypertension and T2DM. This cross-sectional study was conducted to assess the risk factors and lifestyles characteristics associated with type 2 diabetes mellitus among adults in Mwanza city, Tanzania. A multistage random sampling technique was used to obtain 640 male and females respondents aged 30 and above years. Data were collected through face to face interview by using a structured questionnaire which was constructed to solicit information about risk factors and lifestyle characteristics of the respondents. Anthropometric measurements such as height, weight, waist and hip circumferences and total fat and fat free mass were also taken. Random blood glucose and blood pressure levels were measured. Prevalence of overweight in the studied population was 10.5% in males and 18.1% in females. Most females (60.8%; n=79) had waist hip ratio of ≥ 0.85. BMI and body fat were significantly (p˂0.05) related to elevated blood glucose. It was further noted that, relationship between diabetic respondents with their first degree relatives with diabetes was significant (p˂0.05). The relative risk for developing type 2 diabetes mellitus by having first class relative with the disease was RR 2.11, (95% CI: 1.4-3.1). There was a strong (p˂0.05) association between smoking and elevated blood glucose. It can be concluded that it is of utmost importance to intervene, and modify lifestyle behaviours of adults so as to reduce the risks of developing T2DM.