Adults with type 2 diabetes (T2D) who consumed higher amounts of sugar sweetened beverages (SSB) were at increased risk of death from any cause as well as of cardiovascular disease (CVD) and CVD mortality, according to findings of a new prospective cohort study. The risk for all-cause mortality, they report, was 20% greater.
Conversely, the authors observed a significant inverse association with all-cause mortality among study participants who consumed higher amounts of healthier non-sugary beverages, such as coffee, tea, plain water, or low-fat milk, reporting reductions in risk of 26%, 21%, 23%, and 12%, respectively.
The variety of health effects of beverages based on sugar content have been well documented, wrote study authors, led by Qi Sun, MD, associate professor in the departments of nutrition and epidemiology at the Harvard TH Chan School of Public Health. In the general population, low-energy density beverages, eg, water, low-fat milk, are clearly associated with reduced risk of cardiometabolic disease while SSB are associated with higher risk.
Although there are some studies showing positive effects of artificially sweetened beverages (ASB) and coffee or tea on cardiometabolic risk factors among adults with T2D, the association of individual beverage consumption with risk of CVD and mortality in this vulnerable population “remains largely unexplored.”
Their study, the authors wrote in BMJ published online April 19, was designed to explore the association of individual beverage consumption after a diagnosis of T2D as well as of changes in beverage choices before and after T2D diagnosis with subsequent risk of CVD and all-cause mortality. Sun and colleagues also investigated the associations with CVD risk and mortality of substituting beverages one for another.
Study population. The analysis included health professionals with prevalent T2D at baseline from the Nurses’ Health Study (1980 - 2018) and the Health Professionals Follow-Up Study (1986 - 2018), as well as those with a diagnosis of incident T2D during follow-up until 2018. Total participants included in the analysis after exclusions for type 1 diabetes, CVD, or cancer at baseline, and for incomplete dietary information numbered 11 399 from the Nurses’ Health Study and 4087 from the Health Professionals Follow-up Study (74% women; mean age 61 years).
To analyze change in beverage consumption from before to after diagnosis, investigators excluded those with T2D at baseline or those with missing data, leaving 9252 women and 3519 men for the change analysis.
Beverage intake assessment. Beverage consumption was assessed using a validated food frequency questionnaire and updated every 2 to 4 years. Participants were asked how often they had consumed SSBs, ASBs, fruit juice, coffee, tea, low fat milk, full fat milk, or plain water of a prespecified portion size. The primary endpoint analyzed was all-cause mortality and secondary outcomes included CVD incidence and mortality.
All-cause mortality. Over an average of 18.5 years, there was a total of 7638 (49.3%) deaths recorded. Sun and colleagues found that participants with the highest intake of SSBs (>1 serving a day) had a 20% increased risk of all-cause mortality (hazard ratio [HR], 1.20; 95% CI, 1.04 - 1.37) compared with participants with the lowest intake (<1 serving a month). Each additional serving a day increment in SSBs was associated with 8% (95% CI, 2 - 14) higher all-cause mortality.
In contrast, researchers found high intake of certain beverages was associated with lower all-cause mortality: 26% lower for coffee, 21% lower for tea, 23% lower for plain water, and 12% lower for low-fat milk.
There was no clear pattern of association observed for other beverages, such as ASBs, fruit juice, or full-fat milk, according to study results.
Incident CVD. During the mean 18.5-year follow-up, the research team recorded a total of 3447 (22.3%) adults with incident CVD. Similar to findings of all-cause mortality, in the fully adjusted model, higher intake of SSBs was significantly associated with a higher risk of CVD. The multivariable HR of CVD when highest intake was compared with lowest intake was 1.25 (95% CI, 1.03 - 1.51). Also mirroring the all-cause mortality findings, increased consumption of coffee and low-fat milk was inversely associated with CVD incidence, with an 18% and 12% lower risk, respectively.
Coffee connection. Interestingly, Sun et al found an increment in coffee consumption from before to after diagnosis of T2D was significantly associated with a lower risk of all-cause mortality. Participants whose coffee consumption increased after a T2D diagnosis had an 18% lower risk of all-cause mortality compared to those whose consumption of coffee did not change. The patterns of association were similar for both tea (16% lower) and low-fat milk (12% lower).
Beverage substitution. The investigators report that replacing 1 serving/day of SSBs with 1 serving/day of coffee was associated with an 18% lower risk of all-cause mortality and a 20% reduced risk of CVD mortality; replacing SSB with 1 serving/day of tea or of plain water each reduced risk of all cause death by 16% and CVD mortality by 24% and 20% respectively; replacement with low-fat milk conferred a 12% lower risk of all-cause mortality and a 19% lower risk of CVD mortality.
When a serving of ASB replaced 1 of SSB daily, researchers report significant associations of 8% and 15% lower all-cause mortality and CVD mortality, respectively. Replacing one/serving a day of ASBs with coffee, tea, or plain water was also associated with lower all-cause mortality, according to the analysis.
Study strengths, limitations. Writing in an editorial in the same issue, Nita G Forouhi, MD, PhD, of the University of Cambridge School of Clinical Medicine, said “As previous research was conducted in general populations, the new study credibly extends our understanding of the health implications of different beverages to adults with T2D.” She added that large scale long-term randomized trials evaluating interventions of different types and doses of beverage are not practical and applauded Sun and colleagues for the study size, repeated collection of data, lengthy follow-up, and comprehensive adjustment for confounding variables.
Nonetheless, Forouhi detailed unanswered questions such as the effect of adding sugar to coffee or tea, the type of tea preferred, the impact of unexamined popular beverages, and whether results would vary for coronary heart disease and stroke. She also raised concerns about the generalizability of the study findings to other demographic groups, as the study cohort was predominantly white, and to T2D of varying severity.
“Future research should plug these gaps in understanding,” she wrote. “Researchers could also use objective biomarkers to help overcome the limitations of subjective, potentially error prone and biased reporting of beverage consumption.”
Recommendations for future research notwithstanding, Sun and colleagues conclude: “Overall, these results provide additional evidence that emphasizes the importance of beverage choice in maintaining overall health among adults with diabetes.”
Reference: Ma L, Hu Y, Alperet DJ, et al. Beverage consumption and mortality among adults with type 2 diabetes: prospective cohort study. BMJ. 2023;381:e073406. Published online April 19, 2023. doi:10.1136/bmj-2022-073406