Epidemiological modelling of type 2 diabetes in Saudi Arabia :predicted trends and public health implications

PhD thesisBackground: The Kingdom of Saudi Arabia faces one of the highest prevalence rates of type 2 diabetes mellitus (T2DM) in the world. However, there are no credible local data on the trends and future projections of the disease, and the relevant international studies underestimated the true prevalence rates. This thesis used epidemiological modelling to study the trends in T2DM prevalence in Saudi Arabia, predicted its future levels, and quantified the impact of reducing some risk factors on the disease prevalence trends. Methods: This thesis developed and validated the “Saudi IMPACT Diabetes Forecast Model”, which integrates data on the population, obesity and smoking prevalence trends in Saudis aged ≥25 years to estimate the trends in T2DM prevalence (1992-2022) using a Markov modelling approach. The model considers different reasonable scenarios of future trends in obesity prevalence, and incorporates a number of parameters to model the disease epidemiology. These parameters include the estimated diabetes incidence, case-fatality, total mortality, relative risk of diabetes if obese, and relative risk of diabetes if a smoker. The model data inputs and parameters were obtained from different sources, including local departments, medical literature and assumptions. The model results were validated against local data from the STEPwise survey in 2005, and against the model of the Global Burden of Disease study, where the model produced reasonably close results to both of these studies. Results: The prevalence of T2DM among the Saudi population aged ≥25 years was estimated to rise substantially during the 30-year period of 1992-2022 from 8.5% to 39.5%, assuming some levelling off of obesity trends (capping), or to 44.1%, assuming uncapped increasing obesity trends. In men, T2DM prevalence was estimated to increase from 8.7% to 39.2% with capped obesity trends, or to 41.3% with continuing linear increase in obesity trends. In women, T2DM prevalence was estimated to increase from 8.2% to 39.8% with capping of obesity trends, or to 47.7% without such a capping. The model showed that if the trends in obesity start to decline by 10% in 12 years (2010-2022), a relative reduction of 13% in diabetes prevalence could be achieved. If the prevalence of obesity was halted at the 2010 levels, a 10% relative reduction in diabetes prevalence could be attained by 2022. ii Conclusion: T2DM is currently a major public health challenge in Saudi Arabia, and this thesis predicted that its burden will increase substantially in the next decade. Intensive and aggressive preventive measures directed to reduce the levels of risk factors, particularly obesity and smoking, can result in reasonable reduction of the disease prevalence, and therefore should be an urgent action

Comparison of type 2 diabetes prevalence estimates in Saudi Arabia from a validated Markov model against the International Diabetes Federation and other modelling studies

AbstractAimsTo compare the estimates and projections of type 2 diabetes mellitus (T2DM) prevalence in Saudi Arabia from a validated Markov model against other modelling estimates, such as those produced by the International Diabetes Federation (IDF) Diabetes Atlas and the Global Burden of Disease (GBD) project.MethodsA discrete-state Markov model was developed and validated that integrates data on population, obesity and smoking prevalence trends in adult Saudis aged ≥25 years to estimate the trends in T2DM prevalence (annually from 1992 to 2022). The model was validated by comparing the age- and sex-specific prevalence estimates against a national survey conducted in 2005.ResultsPrevalence estimates from this new Markov model were consistent with the 2005 national survey and very similar to the GBD study estimates. Prevalence in men and women in 2000 was estimated by the GBD model respectively at 17.5% and 17.7%, compared to 17.7% and 16.4% in this study. The IDF estimates of the total diabetes prevalence were considerably lower at 16.7% in 2011 and 20.8% in 2030, compared with 29.2% in 2011 and 44.1% in 2022 in this study.ConclusionIn contrast to other modelling studies, both the Saudi IMPACT Diabetes Forecast Model and the GBD model directly incorporated the trends in obesity prevalence and/or body mass index (BMI) to inform T2DM prevalence estimates. It appears that such a direct incorporation of obesity trends in modelling studies results in higher estimates of the future prevalence of T2DM, at least in countries where obesity has been rapidly increasing

Preventing type 2 diabetes mellitus in Qatar by reducing obesity, smoking, and physical inactivity: mathematical modeling analyses.

BACKGROUND: The aim of this study was to estimate the impact of reducing the prevalence of obesity, smoking, and physical inactivity, and introducing physical activity as an explicit intervention, on the burden of type 2 diabetes mellitus (T2DM), using Qatar as an example. METHODS: A population-level mathematical model was adapted and expanded. The model was stratified by sex, age group, risk factor status, T2DM status, and intervention status, and parameterized by nationally representative data. Modeled interventions were introduced in 2016, reached targeted level by 2031, and then maintained up to 2050. Diverse intervention scenarios were assessed and compared with a counter-factual no intervention baseline scenario. RESULTS: T2DM prevalence increased from 16.7% in 2016 to 24.0% in 2050 in the baseline scenario. By 2050, through halting the rise or reducing obesity prevalence by 10-50%, T2DM prevalence was reduced by 7.8-33.7%, incidence by 8.4-38.9%, and related deaths by 2.1-13.2%. For smoking, through halting the rise or reducing smoking prevalence by 10-50%, T2DM prevalence was reduced by 0.5-2.8%, incidence by 0.5-3.2%, and related deaths by 0.1-0.7%. For physical inactivity, through halting the rise or reducing physical inactivity prevalence by 10-50%, T2DM prevalence was reduced by 0.5-6.9%, incidence by 0.5-7.9%, and related deaths by 0.2-2.8%. Introduction of physical activity with varying intensity at 25% coverage reduced T2DM prevalence by 3.3-9.2%, incidence by 4.2-11.5%, and related deaths by 1.9-5.2%. CONCLUSIONS: Major reductions in T2DM incidence could be accomplished by reducing obesity, while modest reductions could be accomplished by reducing smoking and physical inactivity, or by introducing physical activity as an intervention

Forecasting Tunisian type 2 diabetes prevalence to 2027: validation of a simple model.

BACKGROUND: Most projections of type 2 diabetes (T2D) prevalence are simply based on demographic change (i.e. ageing). We developed a model to predict future trends in T2D prevalence in Tunisia, explicitly taking into account trends in major risk factors (obesity and smoking). This could improve assessment of policy options for prevention and health service planning. METHODS: The IMPACT T2D model uses a Markov approach to integrate population, obesity and smoking trends to estimate future T2D prevalence. We developed a model for the Tunisian population from 1997 to 2027, and validated the model outputs by comparing with a subsequent T2D prevalence survey conducted in 2005. RESULTS: The model estimated that the prevalence of T2D among Tunisians aged over 25 years was 12.0% in 1997 (95% confidence intervals 9.6%-14.4%), increasing to 15.1% (12.5%-17.4%) in 2005. Between 1997 and 2005, observed prevalence in men increased from 13.5% to 16.1% and in women from 12.9% to 14.1%. The model forecast for a dramatic rise in prevalence by 2027 (26.6% overall, 28.6% in men and 24.7% in women). However, if obesity prevalence declined by 20% in the 10 years from 2013, and if smoking decreased by 20% over 10 years from 2009, a 3.3% reduction in T2D prevalence could be achieved in 2027 (2.5% in men and 4.1% in women). CONCLUSIONS: This innovative model provides a reasonably close estimate of T2D prevalence for Tunisia over the 1997-2027 period. Diabetes burden is now a significant public health challenge. Our model predicts that this burden will increase significantly in the next two decades. Tackling obesity, smoking and other T2D risk factors thus needs urgent action. Tunisian decision makers have therefore defined two strategies: obesity reduction and tobacco control. Responses will be evaluated in future population surveys