New research presented at the European Association for the Study of Diabetes annual meeting, held in Lisbon, Portugal, found that caffeine can significantly decrease the risk of death among women with diabetes.
The study - which was jointly led by Dr. João Sérgio Neves and Prof. Davide Carvalho, both from the University of Porto in Portugal - examined the link between consuming different amounts of caffeine and mortality risk among men and women with diabetes.
Studying caffeine and death risk
Dr. Neves and team looked at data from the National Health and Nutrition Examination Survey collected between 1999 and 2010. For their study, the researchers examined 1,568 women and 1,484 men with diabetes.
They evaluated the participants' caffeine intake using "24-hour dietary recalls" - that is, interviews that assessed the participants' coffee consumption during the previous 24 hours. Subjects were also asked about the source of their caffeine, be it from coffee, tea, or soft drinks.
The authors used Cox proportional hazard models to adjust for factors that might confound the results, including body mass index (BMI), income and education, alcohol consumption, smoking, high blood pressure, and the number of years that have passed since the diabetes diagnosis.
Drinking two coffees daily cuts death risk
Over the 11-year period, 618 people died. No significant association was found between caffeine consumption and all-cause mortality, cardiovascular mortality, or cancer-related mortality among men.
However, women who had up to 100 milligrams of caffeine - the equivalent of one cup of coffee - every day had a 51 percent lower risk of dying prematurely than women who did not have any caffeine.
The findings were dose-dependent: women who had between 100 and 200 milligrams of caffeine daily were 57 percent less likely to die compared with their non-consuming counterparts.
Furthermore, those who consumed more than 200 milligrams daily - the equivalent of two cups of coffee - had a 66 percent lower risk of death.
Getting one's caffeine intake from tea also had a beneficial effect. "Women who consumed more caffeine from tea had reduced mortality from cancer," write the authors.
More specifically, women who had the highest intake of caffeine from tea were 80 percent less likely to die from cancer compared with women who did not get any caffeine from their tea.
"Our study showed a dose-dependent protective effect of caffeine consumption on all-cause mortality among women," say the authors.
"The effect on mortality appears to depend on the source of caffeine, with a protective effect of coffee consumption on all-cause mortality and cardiovascular mortality, and a protective effect of caffeine from tea on cancer mortality among women with diabetes."
Strengths and limitations of the study
When speaking to Medical News Today about the strengths and limitations of the research, Dr. Neves explained, "We evaluated a cohort of participants from a large database representative of the American population, data was prospectively collected, and hard outcome measures such as death and cause-specific mortality were used."
"Furthermore, we adjusted our analysis for the main biologically plausible confounders," he added.
"As for limitations," Dr. Neves continued, "we assessed caffeine consumption only at the start of the study and we cannot exclude that this data may not represent long-term dietary habits. No adjustment was performed for additives present in caffeine-containing beverages."
Additionally, the authors write in their paper, the "observational study cannot prove that caffeine reduces the risk of death but only suggests the possibility of such a protective effect."
On the possible mechanisms underlying the findings, Dr. Neves told us, "The observed benefits may be directly related to caffeine or to other components present in caffeine-containing beverages."
"Previous studies have shown that consumption of coffee or tea is associated with improved insulin sensitivity and better control of postprandial glycemia in patients with diabetes."
"Furthermore," Dr. Neves added, "the minerals, phytochemicals, and antioxidants present in the caffeine-containing beverages may also contribute to the benefit seen in women's mortality."
"We believe that further studies, with larger cohorts, are indeed needed to confirm [these benefits]," he concluded.