Background: There is an urgent need for effective public health strategies to reduce the burden of type 2 diabetes mellitus (T2DM) in countries with high prevalence, such as Qatar where T2DM prevalence was measured in 2012 at 16.7%.
Aims: The objective of this study was to estimate (for Qataris) the epidemiological impact, on T2DM incidence and prevalence by 2050, of reducing the prevalence of the key T2DM risk factors of obesity, smoking and physical inactivity by 2031. 
Method: We extended a recently developed epidemiological deterministic mathematical model, by adding an intervention component, to estimate the implications of various “what if” scenarios for T2DM prevention. Our model was stratified by sex, age, risk factor status, T2DM status, and intervention status and was parameterized using nationally-representative data. In the modeled intervention scenarios, the prevalence of obesity, smoking and physical inactivity was reduced by various scales; from a “conservative” (10%) to an “ideal” reduction (50%). We also modeled the impact of physical activity as an intervention, beside modelling the reduction in physical inactivity. Physical activity was assumed to reduce the risk of developing T2DM by 20% (by walking) to 50% (by vigorous activity). The epidemiological outcomes from the intervention scenarios were compared to a counterfactual scenario with no intervention.
Results: By 2050, T2DM prevalence reached 24.0% in the counterfactual scenario of no intervention. The intervention scenario implementing the WHO’s Global Action Plan targets of simultaneously halting obesity and reducing smoking and physical inactivity predicted a T2DM prevalence of 21.0%; a 12.0% reduction in T2DM prevalence. This scenario predicted also that 13.2% of new T2DM cases and 3.2% of T2DM mortality cases would be averted by 2050. The intervention scenario modelling a 10-50% reduction in obesity prevalence reduced T2DM prevalence by 7.8-33.7%, averting 8.4-38.9% of new T2DM cases and 2.1-13.2% of T2DM mortality cases by 2050. The intervention scenarios modelling a 10-50% reduction in smoking or physical inactivity prevalence did not lead to large reductions in T2DM prevalence, incidence or mortality. The intervention scenario modelling an increase in the level of physical activity reduced T2DM prevalence by 3.3-9.2%, averting 4.2-11.5% of new T2DM cases and 1.9-5.2% of T2DM mortality cases by 2050.
Discussion: Future T2DM burden among Qataris can be reduced by reducing key T2DM risk factors. The level of reduction depends on the targeted risk factor and scale of reduction. A modest reduction in obesity prevalence can result in considerable reduction in T2DM prevalence, incidence and mortality. Feasibility of implementing such reductions in T2DM risk factors remains to be explored and determined.

Preventing type 2 diabetes mellitus in Qatar by reducing obesity, smoking and physical inactivity: a modeling analysis