In a recent study published in the journal natural medicineresearchers used a new risk assessment model to estimate the absolute and proportional burdens of new cases of type 2 diabetes (T2D) worldwide among adults from 184 countries, in particular direct and body weight-related effects of 11 dietary factors, separately and together.
Study: Incident type 2 diabetes attributable to suboptimal diet in 184 countries. Image Credit: Lightspring / Shutterstock
Background
T2DM is one of the leading causes of death worldwide and has broad socio-economic implications. Between 1980 and 2021, the number of people with diabetes (90% of T2D cases) increased from 108 to 537 million worldwide, with a corresponding increase in obesity among adults.
The incidence of T2D has only increased globally over the past 40 years and continues to rise; if left unchecked, T2D will further deteriorate human health and economic productivity, placing immense pressure on health systems around the world.
Studies have shown direct and weight gain-induced effects of several dietary factors on the etiology of T2DM. Yet the absolute and proportional contributions of suboptimal diet or specific dietary factors to the overall incidence of T2D remain unclear.
About the study
In the current study, researchers estimated the effects of 11 dietary factors, namely insufficient intake of whole grains, fruits, nuts, yogurt, seeds, and (non-starchy) vegetables and excessive consumption of refined wheat and rice, unprocessed red meat, processed meat, sugary drinks (SSB), fruit juices and potatoes on the overall incidence of T2DM.
They made these estimates using food data from the Global Dietary Database (GDD) for adults from 184 countries. The team presented the absolute change in the proportional burden of T2DM attributable to suboptimal diet and each risk factor between 1990 and 2018, stratified globally by world region.
GDD delineated the 184 countries into world regions, which helped researchers specifically discuss T2D trends in the 30 most populous countries for four dietary factors, insufficient consumption of fruits, nuts, seeds and vegetables non-starchy foods, and excessive fruit juice consumption based on weight gain-mediated effects.
They stratified their results according to the age, sex, urbanity and education of the participants. In addition, they stratified country results by socio-demographic index (SDI), a measure of a country’s development. The SDI is expressed on a scale of zero to one based on the average rankings of educational achievement, per capita income and fertility rates.
The researchers used proportional multiplication to estimate the burden of a suboptimal diet, assuming that 50% of the benefits of whole grain intake are due to replacing them with refined wheat and rice. They modeled the effects of eating refined rice and wheat separately, but combined them using proportional multiplication.
The team compared T2D incidence trends between 1990 and 2018 and reported all data as the median and the corresponding 95% IU, based on quantification of uncertainty using 1,000 multi-way probabilistic Monte Carlo simulations.
Results
The study model estimated that in 2018, suboptimal intake of 11 dietary factors led to 14.1 million new cases of T2D worldwide. Excess intake of harmful dietary factors contributed to a higher percentage of this burden than insufficient intake of protective dietary factors (60.8% vs. 39.2%). Insufficient consumption of whole grains led to most T2D cases worldwide (26.1%), followed by excessive consumption of refined wheat and rice (24.6%), processed meat (20.3 %) and unprocessed red meat (20.1%).
The researchers noted marked heterogeneity in the incidence of T2D due to suboptimal overall diet and individual dietary factors at the national and global level. Moreover, they observed an inverse correlation between the incidence of T2DM attributable to diet and age. However, the absolute burden of T2D, assessed per million inhabitants, was highest in middle age, i.e. between 45 and 60 years, indicating an interaction between variations in dietary habits and risk. absolute of T2DM at different ages.
Additionally, some of the dietary factors showed substantial regional heterogeneity. Regionally, the largest increases and decreases in the incidence of diet-attributable T2D occurred in sub-Saharan Africa (+9.3 in absolute percentage points) and in high-income countries (−1. 5%), respectively.
For example, in the Middle East, North Africa (+4.1%) and Sub-Saharan Africa (+3.3%), consumption of refined wheat and rice increased the incidence of T2D, while T2D cases attributable to excess refined rice have decreased in South Asia, Eastern Europe and Central Asia but are increasing due to excessive consumption of refined wheat in these same regions.
The incidence of diet-attributable T2DM was higher in men than in women, in people with higher or lower education, and in urban or rural settings; however, in high-income countries, Central Asia, and Central and Eastern Europe, its incidence of diet-attributable T2DM was higher in less educated people. In populated countries, e.g. Poland and Russia, excessive consumption of red and processed meat and unprocessed potatoes mainly resulted in relatively higher T2D loads. Since the 1990s, the correlation between the incidence of diet-attributable T2DM at the national level and socioeconomic development has become less robust. Latin America and the Caribbean ranks second in the burden of T2DM attributable to diet, particularly Colombia and Mexico, where excessive sugary drinks, excessive consumption of processed meats and insufficient consumption of whole grains resulted in an increased incidence of T2DM.
In areas where diet-attributable T2D burdens are higher among people with higher education, such as high-income countries, education and social security intervention programs should target a nutritious diets to reduce health inequalities related to T2DM. Conversely, in areas where diet-attributable T2D burdens were highest among highly educated adults, such as South Asia, other approaches, such as appropriate labeling of packages, might be more effective. . Financial markets could make a significant contribution to global human health and equity by investing in the production, marketing and sale of products aligned with societal goals.
Data suggests that body mass index (BMI) is increasing rapidly in rural areas of low- and middle-income countries due to the increased supply of processed foods in these areas. Thus, managing these nutritional and health inequalities will require public health interventions and policies tailored to regional circumstances. Notably, the incidence of T2D attributable to the direct etiologic effects of dietary factors was generally higher than their separate BMI-mediated effects. In light of these findings, multisectoral strategies to improve diet quality across the lifespan would remain vital, especially during childhood and adolescence, when people often form lifelong dietary habits.
Whereas in 2018, there was a modest correlation between diet-attributable T2DM burden and SDI (r=0.29) that varied by region of the world. The authors noted a positive correlation in countries in sub-Saharan Africa, South Asia, and high-income countries and a negative correlation in Latin America, Central Asia, Central and Eastern Europe, the Caribbean, and Asia southeast and east. However, this correlation became more robust in 1990 (r = 0.53) than in 2018, and these trends became comparable across all regions of the world. These results highlighted that while diet quality deteriorated in low SDI countries; however, there was no socio-demographic development alongside.
conclusion
The study highlighted carbohydrate quality as an area that needs immediate attention. In particular, excessive consumption of refined rice and wheat and inadequate consumption of whole grains, as two major dietary drivers of T2DM globally, although trends vary over time and by region of the world. In the proportional diet-related T2DM burden, of the 11 dietary factors assessed, excessive consumption of unprocessed red meat contributed the most to the overall increase in T2DM incidence. In conclusion, these findings should inform clinical and public health planning to improve diet quality globally to reduce the global burden of T2DM.
