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From the Journals

Study Links Coffee Timing to Mortality Risk in Diabetes

A temporal link between coffee timing and mortality reveals that drinking coffee between 5:00-8:00 AM was associated with a 41% higher risk of cardiovascular mortality in patients with diabetes, while consumption between 8:00 AM-noon reduced risk by 21%.

Conexiant

A large observational study found associations between the timing of coffee and tea consumption and mortality risk among patients with diabetes.

In the study, published in BMC Medicine, investigators analyzed data from 5,378 participants with diabetes in the U.S. National Health and Nutrition Examination Survey (2003 to 2014), following outcomes through December 2019. During 47,361 person-years of follow-up, they documented 1,639 deaths, including 731 from cardiovascular disease (CVD).

The study found that drinking coffee between dawn and forenoon (5:00 AM to 8:00 AM) was associated with increased mortality risk:

  • All-cause mortality (hazard ratio [HR] = 1.25, 95% confidence interval [CI] = 1.05–1.50)
  • CVD mortality (HR = 1.41, 95% CI = 1.07–1.86)
  • Heart disease mortality (HR = 1.47, 95% CI = 1.05–2.07)
  • Diabetes mortality (HR = 1.50, 95% CI = 1.10–2.04).

Coffee consumption between forenoon and noon (8:00 AM to 12:00 PM) was associated with reduced mortality risk:

  • All-cause mortality (HR = 0.80, 95% CI = 0.69–0.92)
  • CVD mortality (HR = 0.79, 95% CI = 0.63–0.99)
  • Heart disease mortality (HR = 0.70, 95% CI = 0.52–0.94).

Tea consumption showed similar associations when consumed between forenoon and noon, with reduced CVD mortality risk (HR = 0.62, 95% CI = 0.44–0.87).

The investigators controlled for multiple variables including age, sex, race, education, lifestyle factors, body mass index, and various health conditions. The study included adults with diabetes defined by self-reported diagnosis, medication for hyperglycemia, HbA1c ≥ 6.5%, fasting glucose ≥ 7.0 mmol/L, or random/2-h OGTT glucose ≥ 11.1 mmol/L.

Consumption patterns showed:

  • 39.4% were non–coffee drinkers
  • 19.6% consumed coffee during dawn to forenoon
  • 26.5% during forenoon to noon
  • 7.6% during noon to evening
  • 6.9% during evening to dawn.

Early morning coffee drinkers showed distinct characteristics, including higher rates of smoking and alcohol consumption, irregular exercise habits, elevated systolic blood pressure, and older age.

The study noted several limitations:

  • Reliance on self-reported 24-hour dietary recall
  • Inability to distinguish between type 1 and type 2 diabetes
  • No differentiation between coffee types (caffeinated, decaffeinated, and instant)
  • No distinction between tea varieties.

Sensitivity analyses confirmed the findings remained consistent after:

  • Excluding participants with less than 2 years follow-up
  • Adjusting for caffeine intake
  • Controlling for insulin resistance
  • Excluding participants who consumed beverages at multiple times.

The study represented the first large-scale investigation examining associations between beverage timing and mortality outcomes in patients with diabetes.

The authors declared no competing interests.