Common drinks cause 20% more mortality among diabetic patients! What can I drink to reduce my risk?

▎WuXi AppTec content team editor

In 2021, approximately 537 million adults worldwide had diabetes, and this number is expected to rise to 783 million by 2045. The risk of comorbidities such as cardiovascular and premature death is particularly increased in adults with type 2 diabetes. Dietary interventions play an important role in glycaemic control in adults with type 2 diabetes.

Depending on the amount of sugar and other ingredients, different types of beverages may have different health effects. A recent study published in The BMJ evaluated the relationship between intake of specific types of beverages and mortality and cardiovascular disease outcomes in adults with type 2 diabetes. The results showed that coffee, tea, plain water and low-fat milk were associated with a lower risk of cardiovascular disease or premature death in adults with type 2 diabetes, while excessive intake of sugar-sweetened beverages was the opposite.

The study was led by scholars from Harvard University in the United States, and completed by teams such as the University of Toronto, Xi'an Jiaotong University in China, and Huazhong University of Science and Technology. Professor Qi Sun of Harvard University School of Public Health is the corresponding author, Professor Ma Le of the School of Public Health of Xi'an Jiaotong University Health Science Center is the first author, and other authors include Professor Frank B. Hu, Academician of the National Academy of Medical Sciences, Professor Hua B. Hu of Harvard University, and Professor Liu Gang of the School of Public Health, Tongji Medical College of Huazhong University of Science and Technology.

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Due to altered metabolism of carbohydrates and other macronutrients in adults with diabetes, general dietary recommendations and nutritional guidelines for the general population may not be directly applicable to adults with diabetes. Therefore, it is important to assess the relationship between various dietary intakes and disease outcomes and mortality in adults with diabetes. The study focused on the effects of multiple beverages: (1) sugar-sweetened beverages, (2) artificially sweetened (sugar substitute) beverages that contain little sugar or calories; (3) Low energy density drinks such as plain water, low-fat milk and coffee; (4) Common drinks such as fruit juice and whole milk.

The study included a total of 15,486 patients diagnosed with type 2 diabetes at baseline and during the follow-up period from the Nurses' Health Study (1980~2018, 11,399 cases) and the Health Professionals Follow-up Study (1986~2018, 4087 cases). The research team assessed beverage intake using a validated food frequency questionnaire and updated the data every two to four years. The primary outcomes were all-cause mortality, and the secondary outcomes were cardiovascular morbidity and mortality.

Different beverages and risk of death

During follow-up, researchers recorded a total of 7638 (49.3%) deaths.

▲High intake of sugar-sweetened beverages was significantly associated with higher all-cause mortality. The risk of all-cause mortality was increased by 20% in those with the highest intake of sugar-sweetened beverages compared with those with the lowest intake of sugar-sweetened beverages (HR 1.20 [95% CI: 1.04~1.37]).

Conversely, high intake of low energy density beverages is associated with lower mortality:

●Coffee consumption was associated with a 26% lower risk of death (HR 0.74 [95% CI: 0.63~0.86]);

● Drinking more tea was associated with a 21% reduction in the risk of death (HR 0.79 [95% CI: 0.71~0.89]);

● Drinking plain water was associated with a 23% reduction in the risk of death (HR 0.77 [95% CI: 0.70~0.85]);

● Drinking low-fat milk was associated with a 12% reduction in the risk of death (HR 0.88 [95% CI: 0.80~0.96]).

The researchers did not find a clear association between other beverages, such as artificial sweetener [sugar substitute] drinks, fruit juices or whole milk, and the risk of death.

▲ The results of multivariate correction showed that the risk of all-cause mortality decreased nonlinearly with the increase of coffee, tea, plain water and low-fat milk intake (nonlinear mean P<0.001). The relationship between sugar-sweetened beverages and all-cause mortality is more linear. All-cause mortality increased by 8% for each additional serving/day of sugar-sweetened beverages (HR 1.08 [95% CI: 1.02~1.14]).

▲ After a diagnosis of diabetes, switching to healthier beverages can also reduce the risk of all-cause death. For example, participants who increased coffee intake after a diabetes diagnosis had a 18% lower risk of all-cause mortality compared with participants with unchanged coffee intake. Similar patterns of association were observed in tea and low-fat milk.

Different beverages and cardiovascular disease risk

During follow-up, researchers recorded a total of 3447 (22.3%) adult subjects with cardiovascular disease.

▲ The investigators separately assessed the association between specific types of beverage intake and cardiovascular morbidity and mortality, and the association pattern was largely similar to that of all-cause mortality.

In the fully adjusted model, higher intake of sugar-sweetened beverages was associated with higher cardiovascular morbidity and mortality. Compared with the population with the lowest intake of sugar-sweetened beverages, the incidence of cardiovascular disease and mortality were increased by 25% (HR 1.25 [95% CI: 1.03~1.51]) and 29% (HR 1.29 [95% CI: 1.02~1.63]), respectively, compared with the population with the lowest intake of sugar-sweetened beverages. Conversely, increased intake of coffee and low-fat milk was inversely associated with the incidence of cardiovascular disease: the risk ratio was 0.82 (95% CI: 0.69~0.98) for coffee and 0.88 (95% CI: 0.78~1.00) for low-fat milk.

The researchers further evaluated the health effects of beverage substitution for each other, when one serving of sugar-sweetened beverages was replaced daily to the following other beverages:

● Switching to one cup of coffee per day reduced the risk of all-cause mortality by 18% (95% CI: 12%~23%), and the risk of death from cardiovascular disease by 20%;

● Switching to one tea per day reduced the risk of all-cause mortality by 16% (95% CI: 9%~22%) and the risk of death from cardiovascular disease by 24%.

● Changing to one serving of plain water per day reduced the risk of all-cause death by 16% (95% CI: 10%~21%), and the risk of death from cardiovascular disease by 20%;

● Changing to one serving of low-fat milk per day reduced the risk of all-cause mortality by 12% (95% CI: 5%~17%) and the risk of death from cardiovascular disease by 19%.

The replacement of one serving of sugar-sweetened beverages per day with artificially sweetened beverages was also significantly associated with an 8% (95% CI: 1%~14%) and 15% (95% CI: 4%~24%) reduction in all-cause mortality and cardiovascular mortality, respectively. Replacing one serving of artificially sweetened beverages per day with coffee, tea, or plain water was also associated with a reduction in all-cause mortality.

Overall, higher intake of sugar-sweetened beverages was associated with higher all-cause mortality and cardiovascular morbidity and mortality in adults with type 2 diabetes, while intake of coffee, tea, plain water, and low-fat milk was inversely associated with all-cause mortality. These findings highlight the potential role of healthy beverage choices in managing the risk of cardiovascular disease and premature death in adults with type 2 diabetes.

Professor Nita G Forouhi, a nutritional epidemiologist at the University of Cambridge, wrote a contemporaneous review of the study, pointing out that this study extended the understanding of the health effects of different beverages to people with type 2 diabetes with convincing results. Another important information is that because the results of this study in the population with type 2 diabetes are broadly similar to previous results in the general population, there is no need for additional special beverage restrictions for people with type 2 diabetes.