Drinking coffee might reduce diabetes risk in some women

Habitual coffee drinking may lower type 2 diabetes risk for women with a history of gestational diabetes, according to experts.

Previous research has examined connections between gestational diabetes and type 2 diabetes risk and, separately, shown that moderate coffee consumption can lower mortality risk. To better understand how coffee consumption might affect type 2 diabetes risk, Jiaxi Yang, a postdoctoral research fellow at the National University of Singapore, and colleagues, conducted the prospective study and published their findings in the American Journal of Clinical Nutrition.

The researchers wrote that “overall, epidemiological studies across diverse populations have consistently reported the benefits of coffee, including both caffeinated and decaffeinated coffee, on lowering” the risk for type 2 diabetes.

“Individuals with a history of GDM are at exceptionally higher risk of T2D than the general population. Although past studies examined coffee consumption pre- or during pregnancy with risk of GDM or coffee consumption with risk of T2D in the general population, we are unaware of any studies examining post-GDM coffee consumption with long-term T2D risk among these individuals at high risk,” they wrote.

For the study, Yang and colleagues followed 4,522 women, most of whom were white, with a history of gestational diabetes between 1991 and 2017, updating demographic and lifestyle factors like disease outcomes and diet every 2 to 4 years. The participants reported their coffee consumption through validated food frequency questionnaires. Additionally, the researchers collected fasting blood samples from a subset of diabetes-free patients in 2012 to 2014 so they could measure glucose metabolism biomarkers (insulin, HbA1c, C-peptide; n = 518).

In the median follow-up period of 23.9 years, 979 people developed type 2 diabetes. Yang and colleagues reported that drinking one cup of caffeinated coffee every day instead of a serving of an artificially sweetened beverage was associated with a 9% (risk ratio [RR] = 0.91, 95% CI, 0.84-0.99) lower risk for type 2 diabetes. Replacing a sugar-sweetened beverage conferred more benefits, with a 17% (RR = 0.83, 95% CI, 0.75-0.93) lower risk.

The adjusted HR for less than one, two to three, and four or more cups per day compared with zero cups per day was 0.91 (95% CI, 0.78-1.06), 0.83 (95% CI, 0.69-1.01) and 0.46 (95% CI, 0.28-0.76), respectively.

Additionally, the researchers noted that higher caffeinated coffee consumption was linked to lower fasting insulin and C-peptide concentrations (all P-trend < .05). Decaffeinated coffee, on the other hand, was not significantly associated with type 2 diabetes, “but was inversely associated with C-peptide concentrations (P trend = 0.003).”

“This current study presents complementary findings on the inverse associations of coffee, particularly caffeinated coffee, with T2D progression for high-risk individuals with a history of GDM,” Yang and colleagues wrote. “However, our observation on the null findings for decaffeinated coffee was in contrast to the literature evidence, possibly due to the overall low consumption levels in this cohort.”

The researchers concluded that “among predominantly Caucasian females” who have a history of gestational diabetes, increased caffeinated coffee intake was linked to a lower type 2 diabetes risk “and a more favorable metabolic profile.”

“Given the epidemiological evidence on the detrimental effects of added sugar and the moderately protective associations between low-fat dairy consumption and T2D risk, coffee, when consumed properly at moderate levels (three to five cups/d), may be considered as a healthier beverage option compared with the other less healthy beverages among individuals with a history of GDM,” they wrote. “Coffee might be promoted as an alternative to other less healthy beverages and be incorporated into a healthy lifestyle to prevent T2D progression for individuals with a history of GDM.”