Type-2 Diabetes mellitus is one of the most alarming diseases in both developed and developing countries. The WHO predicted that 90% of people around the globe will suffer from T2DM (WHO, 2016). Most of the people are living in India without knowing that they are affected with T2DM. So, the undiagnosed T2DM leads to the complication in heart, kidney disease, eye and feet. Even though Type 2 diabetes has many risk factors associated to it, lifestyle changes play a vital role in triggering the Type 2 diabetes. Hence, the objective of the present study is to analyze and identify the most influencing risk factors of T2DM. Determining the most influencing risk factor of T2DM is not an easy task as there are lot of complexity and uncertainty involved in it. To tackle this issue, a novel decision making system is designed by combining the salient features of The Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) and Fuzzy Cognitive Map (FCM). Eight risk factors are chosen as the input variables for the system. The proposed system elucidates that Blindness, Obesity, Physical Inactivity are the most influencing factors for the type 2 diabetes mellitus. © 2019 Author(s).