Study Estimates 7 of 10 Global Cases of Diabetes Linked to Poor Diet

Dariush Mozaffarian, MD, DrPH
Credit: Friedman School of Nutrition Science and Policy

A new study from the Tufts University Friedman School of Nutrition Science and Policy suggests poor diet was responsible for 7 of every 10 cases of type 2 diabetes (T2D) in the world.

Funded by the Bill and Melinda Gates Foundation, results of the study, which used a risk assessment model based on 11 dietary factors for 184 countries, suggests suboptimal diet was responsible for 14.1 million cases of incident between 1990 and 2018—a number representative of 70.3% of new cases globally.¹

“Our study suggests poor carbohydrate quality is a leading driver of diet-attributable type 2 diabetes globally, and with important variation by nation and over time,” said senior investigator Dariush Mozaffarian, MD, DrPH, the Jean Mayer Professor of Nutrition and dean for policy at the Friedman School.² “These new findings reveal critical areas for national and global focus to improve nutrition and reduce devastating burdens of diabetes.”

In the 21st century, few public health crises have placed an equivalent burden on health systems as T2D. With a multitude of studies, including a study published in January 2023 projecting rates to increase from more than 600% by 2060,³ illustrating ballooning rates of the condition, many have begun to hypothesize specific causes around this, now, global epidemic.

In the current study, Mozaffarian and an international team of investigators sought to determine the proportion of T2D cases attributable to suboptimal diet using data from the Global Dietary Database (GDD) from 1990 through 2018. A global database with data from 185 countries dating back to 1990, the GDD boasts nearly 1500 survey-years of individual-level dietary intake data.⁴

Together, with the GDD, along with the NCD Risk Factor Collaboration and the Global Burden of Disease study, investigators developed a risk assessment model to estimate the absolute and proportional burden of new T2D in adults globally and by age, sex, education, urbanicity, world region and nation, in 1990 and 2018.¹

For the purpose of analysis, investigators designed their model to estimate the diet attributable burden based on 11 dietary factors. These factors were whole grains, refined grains, processed meats, unprocessed red meats, yogurt, potatoes, fruit, nuts and seeds, non-starchy vegetables, fruit juice, and sugar-sweetened beverages.¹

Upon analysis, the largest T2D burdens observed in the study were attributable to insufficient intake of whole grains at 26.1% (95% uncertainty interval [UI], 25.0-27.1) followed by excess intake of refined rice and wheat at 24.6% (95% UI, 22.3-27.2), excess intake of processed meats at 20.3% (95% UI, 18.3-23.5), and excess intake of unprocessed red meats at 20.1% (95% UI, 19.0-21.2%). Investigators pointed out the lowest attributable burdens were seen for excess intake of fruit juice (0.09% [95% UI, 0.09-0.1]), insufficient intake of non-starchy vegetables (0.9% [95% UI, 0.9-1.0]), and insufficient intake of nuts and seeds (1.1% [95% UI, 1.1-1.2]).¹

When assessing trends across different regions, investigators found the highest proportional burdens were seen central and eastern Europe and central Asia (85.6% [95% UI, 83.4-87.7]) and Latin America and the Caribbean (81.8% [95% UI, 80.1-83.4]). In contrast, the lowest proportional burdens were observed in sub-Saharan Africa (68.1% [95% UI, 64.3-72.7]) and South Asia (55.4% [95% UI, 52.1-60.7]).¹

Further analysis suggested proportions of diet attributable T2D were generally larger among men than among women and were inversely correlated with age. Additionally, for those in high-income countries, which included the United States, results suggested the diet-attribute T2D burdens were larger among rural residents and lower-educated individuals. Investigators underscored the diet-attributable in 2018 represented a 2.6 absolute percentage point increase, which translates to 8.6 million more cases, from the diet-attributable burden in 1990.¹

“Left unchecked and with incidence only projected to rise, type 2 diabetes will continue to impact population health, economic productivity, health care system capacity, and drive heath inequities worldwide,” said lead investigator Meghan O’Hearn, PhD, impact director for Food Systems for the Future.² “These findings can help inform nutritional priorities for clinicians, policymakers, and private sector actors as they encourage healthier dietary choices that address this global epidemic.”

References:

1. O'Hearn M, Lara-Castor L, Cudhea F, et al. Incident type 2 diabetes attributable to suboptimal diet in 184 countries [published online ahead of print, 2023 Apr 17]. Nat Med. 2023;10.1038/s41591-023-02278-8. doi:10.1038/s41591-023-02278-8
2. TuftsPR. Study links poor diet to 14 million cases of type 2 diabetes globally. EurekAlert! https://www.eurekalert.org/news-releases/986055. Published April 17, 2023. Accessed April 18, 2023.
3. Tönnies T, Brinks R, Isom S, et al. Projections of Type 1 and Type 2 Diabetes Burden in the U.S. Population Aged <20 Years Through 2060: The SEARCH for Diabetes in Youth Study. Diabetes Care. 2023;46(2):313-320. doi:10.2337/dc22-0945
4. Welcome to the global dietary database: Global dietary database. Welcome to the Global Dietary Database | Global Dietary Database. https://www.globaldietarydatabase.org/. Accessed April 18, 2023.