This review discussed the prevalence of diabetes mellitus (DM) in Malaysia and the associated major risk factors, namely overweight/obesity, dietary practices and physical activity in both adults and school children. Detailed analyses of such information will provide crucial information for the formulation and implementation of programmes for the control and prevention of T2DM in the country. National studies from 1996-2015, and other recent nation-wide studies were referred to. The current prevalence of DM in 2015 is 17.5%, over double since 1996. Females, older age group, Indians, and urban residents had the highest risk of DM. The combined prevalence of overweight/obesity in 2015 is 47.7% for adults. Adults did not achieve the recommended intakes for majority of the foods groups in the Malaysian Food Pyramid especially fruits and vegetables. Adults also had moderate physical activity level. Three nation-wide studies showed a prevalence ranging from 27 to 31% for combined overweight/obesity in school children. The prevalence was higher among boys, primary school age, Indian ethnicity, and even rural children are not spared. Physical activity level was also low among school children. There must be serious systematic implementation of action plans to combat the high prevalence of diabetes and associated risk factors.