Beverage consumption and mortality among adults with type 2 diabetes Original paper

In this cohort study of adults with type 2 diabetes, a higher intake of sugar-sweetened beverages was associated with an increased risk of all-cause death, whereas higher intakes of tea, coffee, plain water, and low-fat milk were associated with a decreased risk.

The association between beverage consumption and all-cause mortality, cardiovascular disease (CVD) mortality, and CVD incidence.

15,486 U.S. adults with type 2 diabetes (average age of 61 years, 74% women, 26% men) from the Nurses’ Health Study (1980–2018) and Health Professionals Follow-Up Study (1986–2018).

The researchers conducted a prospective cohort study over an average follow-up duration of 18.5 years. They compared the lowest intake of beverages (less than 1 serving/month) with the highest intake level (more than 1 serving/day) of popular beverages, including tea, coffee, plain water, fruit juice, low-fat milk, full-fat milk, sugar-sweetened beverages (SSBs), and artificially sweetened beverages (ASBs).

The researchers also analyzed whether a dose-response relationship between consumption level and all-cause mortality exists and whether replacing SSBs with other beverages or changing coffee and tea intake over time (after being diagnosed with diabetes) influenced the outcomes.

The analyses were adjusted for age, sex, diet quality, energy intake, physical activity, smoking status, alcohol consumption, and duration of diabetes, among other factors.

Participants who frequently consumed SSBs (more than 1 serving/day) had an increased risk of all-cause mortality (+20%), CVD mortality (+29%), and CVD incidence (+25%) compared to participants with low intake levels (less than 1 serving/month). In contrast, regular consumption of tea (−21%), coffee (−26%), plain water (−23%), and low-fat milk (−12%) was linked to a decreased risk of all-cause mortality. No significant associations were found for fruit juice.

In the dose-response analysis, the risk of all-cause mortality increased for each additional daily serving of SSBs (+8%) and full-fat milk (+12%), but decreased for each additional daily serving of tea (−6%), coffee (−9%), plain water (−6%), and low-fat milk (−3%). Moreover, the risk of incident CVD decreased for each additional daily serving of coffee (−4%).

A decreased risk of all-cause mortality was found for participants who replaced one serving of SSBs per week with tea (−16%), coffee (−18%), plain water (−16%), low-fat milk (−12%), and ASBs (−8%) compared to those who did not change their beverage consumption level. Participants who increased their coffee intake after being diagnosed with diabetes also had a lower risk of all-cause mortality (−18%) compared to those who did not change their coffee consumption.

Beverage consumption and mortality among adults with type 2 diabetes

Scientific evidence has consistently demonstrated that beverages with varying sugar content and bioactive compounds can have varying health effects. For example, meta-analyses of prospective cohort studies have established a strong association between high consumption of beverages with low energy density and a reduced risk of overall and cause-specific mortality in the general population, including tea,^[1] coffee,^[2] plain water,^[3] and low-fat milk.^[4] Conversely, the intake of SSBs and ASBs has been linked to an increased risk of mortality.^[5]

However, the association between individual beverage consumption and mortality among adults with type 2 diabetes remained largely unexplored. The present meta-analysis expands the current body of research, suggesting that beverage choices among adults with type 2 diabetes can influence their mortality risk. There are several biological mechanisms that can help explain these findings.

The higher mortality risk associated with the intake of SSBs may be attributed to the higher consumption of fructose in liquid form. The calories from SSBs may not provide the same level of satiety as solid foods, leading to an incomplete reduction in energy intake and, consequently, a lack of suppression in the consumption of other foods, resulting in weight gain.^[6] SSBs, which typically contain added sucrose or high fructose corn syrup, can thus contribute to obesity, insulin resistance, and inflammation — all of which are associated with higher mortality risk.^[7][8][9]

On the other hand, the consumption of tea and coffee has been linked to a lower risk of overall mortality, and coffee specifically has been associated with a lower risk of CVD mortality. The beneficial effects of tea and coffee may be attributable to their high content of bioactive compounds, such as polyphenols. Tea, for example, contains high amounts of catechins, while coffee contains chlorogenic acids, both of which are suspected to possess antioxidant and anti-inflammatory properties. This may be why previous research has shown that replacing SSBs with tea or coffee (250 g/day) is associated with a 22% and 21% lower incidence of type 2 diabetes, respectively.^[10] Randomized controlled trials have further supported these mechanisms by demonstrating that supplemental green tea extract improves arterial stiffness in adults with type 2 diabetes,^[11] and supplemental coffee extract improves glycemic control and insulin resistance.^[12]

The findings of the present study differ from previous research in regard to ASBs. While this meta-analysis found no association, a previous meta-analysis reported an increased risk of mortality associated with ASB consumption.^[5] However, in the present meta-analysis, replacing one serving of SSBs per week with ASBs was associated with an 8% decreased risk of all-cause mortality compared to participants who did not change their beverage consumption. It is worth noting that previous research has shown the opposite: replacing SSBs with ASBs was linked to an increased risk of all-cause and CVD mortality in one study involving the general population.^[13]

How should these seemingly contradictory findings be interpreted? One limitation of previous research is that it has primarily relied on observational data, which can establish associations but is limited in its ability to infer causal relationships. However, there is also clinical evidence to consider. For example, a meta-analysis of randomized controlled trials found that consuming ASBs had no effect on blood glucose levels.^[14] This suggests that consuming ASBs is generally safe for adults with type 2 diabetes. Nonetheless, additional research is needed to validate this assumption and provide more conclusive evidence.

Overall, the research is generally consistent with the idea that beverage choice influences mortality risk. The present study showed that this idea also applies to U.S. adults with type 2 diabetes. The consistency of the evidence also suggests that the metabolic state characteristic of type 2 diabetes does not play a critical role in modifying the associations between beverages and health outcomes, as the findings in this study seem to generally apply to people without diabetes as well.

Although this study has several strengths, such as large sample size and long follow-up durations, it also has several limitations:

• The analysis did not consider potential interactions between beverage intake and other lifestyle factors, such as sleep or stress.
• The researchers focused solely on all-cause mortality and CVD, but exploring associations with other health conditions associated with type 2 diabetes (e.g., diabetic nephropathy, retinopathy, or neuropathy) would have provided a more comprehensive understanding of the potential health effects of beverage consumption among this population.
• The study population consisted of healthcare professionals, so its findings may not be applicable to the general population.