Groundbreaking study links diet and type 2 diabetes across 184 countries globally

[Apr. 18, 2023: JJ Shavit, The Brighter Side of News]

Poor diet contributed to over 14.1 million cases of type 2 diabetes in 2018, representing over 70% of new diagnoses globally, according to a research model of dietary intake in 184 countries developed by researchers at the Friedman School of Nutrition Science and Policy at Tufts University. The study, which provides valuable insight into which dietary factors are driving type 2 diabetes burden by world region, was published in the journal Nature Medicine.

The analysis looked at data from 1990 and 2018 and identified three factors that had an outsized contribution to the rising global incidence of type 2 diabetes: insufficient intake of whole grains, excesses of refined rice and wheat, and the overconsumption of processed meat. Drinking too much fruit juice and not eating enough non-starchy vegetables, nuts, or seeds had less of an impact on new cases of the disease.

The senior author, Dariush Mozaffarian, Jean Mayer Professor of Nutrition and dean for policy at the Friedman School, says, “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. These new findings reveal critical areas for national and global focus to improve nutrition and reduce devastating burdens of diabetes.”

Of the 184 countries included in the Nature Medicine study, all saw an increase in type 2 diabetes cases between 1990 and 2018, representing a growing burden on individuals, families, and healthcare systems. Type 2 diabetes is characterized by the resistance of the body’s cells to insulin.

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The research team based their model on information from the Global Dietary Database, along with population demographics from multiple sources, global type 2 diabetes incidence estimates, and data on how food choices impact people living with obesity and type 2 diabetes from multiple published papers.

The analysis revealed that poor diet is causing a larger proportion of total type 2 diabetes incidence in men versus women, in younger versus older adults, and in urban versus rural residents at the global level.

Regionally, Central and Eastern Europe and Central Asia, particularly in Poland and Russia, where diets tend to be rich in red meat, processed meat, and potatoes, had the greatest number of type 2 diabetes cases linked to diet. Incidence was also high in Latin America and the Caribbean, especially in Colombia and Mexico, which was credited to high consumption of sugary drinks, processed meat, and low intake of whole grains.

Regions where diet had less of an impact on type 2 diabetes cases included South Asia and Sub-Sharan Africa, though the largest increases in type 2 diabetes due to poor diet between 1990 and 2018 were observed in Sub-Saharan Africa. Of the 30 most populated countries studied, India, Nigeria, and Ethiopia had the fewest case of type 2 diabetes related to unhealthy eating.

“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 health inequities worldwide,” says first author Meghan O’Hearn, Impact Director for Food Systems for the Future, a non-profit institute, and for-profit fund that enables innovative food and agriculture enterprises to measurably improve nutrition outcomes for underserved and low-income communities. “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.”

Other recent studies have estimated that 40% of type 2 diabetes cases globally are attributed to suboptimal diet, lower than the 70% reported in the Nature Medicine paper. The research team attributes this to the new information in their analysis, such as the first ever inclusion of refined grains, which was one of the top contributors to diabetes burdens.

The team's findings also shed light on the fact that the burden of type 2 diabetes related to poor diet is increasing at an alarming rate. According to the study, the global number of new cases of type 2 diabetes related to unhealthy eating habits increased by 25% between 1990 and 2018, from 9.2 million to 11 million.

The researchers also identified some key dietary factors that contribute to the increasing burden of type 2 diabetes. They found that insufficient intake of whole grains, excess consumption of refined grains such as rice and wheat, and overconsumption of processed meat were among the top contributors to the rising incidence of the disease globally.

Dr. Dariush Mozaffarian, the senior author of the study and Jean Mayer Professor of Nutrition and dean for policy at the Friedman School, emphasized the importance of these findings, stating that "poor carbohydrate quality is a leading driver of diet-attributable type 2 diabetes globally, and with important variation by nation and over time."

The study also highlighted some geographical variations in the impact of poor diet on the burden of type 2 diabetes. For example, Central and Eastern Europe and Central Asia had the highest number of cases related to poor diet, with Poland and Russia being the worst affected countries due to their high consumption of red and processed meat and potatoes. Meanwhile, Latin America and the Caribbean had a high incidence of type 2 diabetes due to excessive consumption of sugary drinks, processed meat, and low intake of whole grains.

However, South Asia and Sub-Saharan Africa had a relatively lower impact of poor diet on the burden of type 2 diabetes, although there was a significant increase in type 2 diabetes due to poor diet between 1990 and 2018 in Sub-Saharan Africa. India, Nigeria, and Ethiopia were found to have the fewest cases of type 2 diabetes related to unhealthy eating.

The study also found that poor diet was causing a larger proportion of total type 2 diabetes incidence in men than in women, in younger adults versus older adults, and in urban residents compared to rural residents globally.

The researchers used data from the Global Dietary Database and population demographics from multiple sources to develop their model. They also relied on global type 2 diabetes incidence estimates and data on how food choices impact people living with obesity and type 2 diabetes from multiple published papers.

The researchers hope that their findings will help inform nutritional priorities for clinicians, policymakers, and private sector actors, and encourage healthier dietary choices that address this global epidemic. They also noted that their estimates were subject to uncertainty and could be refined as new data emerges.

It is clear from the study that the burden of type 2 diabetes related to poor diet is a major public health issue that needs urgent attention. With the incidence of the disease projected to rise further, addressing this issue should be a top priority for policymakers, clinicians, and public health professionals worldwide.

Note: Materials provided above by The Brighter Side of News. Content may be edited for style and length.

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