Good news for women who love coffee.
Those who drink 4 or more cups of caffeinated coffee daily have a markedly lower risk of developing type 2 diabetes compared with those who drink less than one.
That’s the conclusion from a recent prospective study involving 4,522 women with prior histories of gestational diabetes, who were tracked during the 26-year period between 1991 and 2017.
A collaboration between researchers at the National University of Singapore, and the Harvard School of Public Health, this project gathered extensive demographic, diet, and lifestyle data every two years, and studied T2D incidence as a function of various diet variables. From a subset of 518 participants, the researchers also measured blood markers of glucose metabolism (HbA1c, insulin, C-peptide).
During the decades-long course of the study, 979 (21.6%) of the women were diagnosed with T2D.
The exact mechanisms by which coffee affects glucose metabolism are not entirely clear, but they do seem to be linked to caffeine. Decaf coffee did not confer the same risk reduction.
After adjusting for demographic and age variables, and using a multivariate Cox regression model, the investigators saw a clear inverse relationship between caffeine intake and diabetes risk.
Compared to the women who never drank coffee, those who routinely drank 4 or more cups had a 54% lower likelihood of developing T2D (hazard ratio 0.46). Those who habitually drank 2-3 cups had a 17% lower risk (hazard ratio 0.83). One or fewer cups daily, shaved the risk by a mere 9% (hazard ratio 0.91).
Higher caffeinated coffee consumption was associated with lower fasting insulin and C-peptide concentrations (Yang J, et al. Am J Clin Nutr 2022).
“Replacement of 1 serving per day of sugar-sweetened beverage and artificially sweetened beverage with 1 cup per day of caffeinated coffee was associated with a 17% and 9% lower risk of T2D, respectively,” the authors point out.
The exact mechanisms by which coffee affects glucose metabolism so as to reduce diabetes risk are not entirely clear, but they do seem to be linked to caffeine. Decaffeinated coffee did not seem to confer the same risk reduction, though decaf consumption did show an inverse associated with C-peptide concentrations.
Yang and colleagues also point out that the study participants were predominantly White. The risk mitigating effect may not be fully generalizable to women of other races or ethnicities.