The present study determined the effects light, medium, and dark roasted, brewed coffees on blood glucose responses in normal (n = 19) subjects.

This is a single-blinded, randomized partial block design conducted over 6 weeks in two parts.

In part 1 (3 weeks), participants were randomly assigned to consume four beverages: a placebo containing water and caramel color, light, medium, or dark roast coffee before, during, or after consumption of a beverage containing 50 g of glucose.

In part 2 (3 weeks), participants were randomly assigned to consume four beverages: a placebo containing water and caramel color, light, medium, or dark roast coffee before, during, or after consumption of a standardized breakfast (corn flakes cereal + skim milk) containing 50 g of glucose.

In each part, fasting and postprandial glucose profiles were determined.

Inclusion Criteria:

• Age 18-64 years old with BMI less than 29 and fasting blood glucose less than 125 mg/dl.

Exclusion Criteria:

• Age 18-64 years old with BMI less than 29 and fasting blood glucose less than 125 mg/dl.

• Weight less than 110 pounds (55 kg)

• Pre-existing health conditions, such as:

  • High cholesterol
  • Hypertension
  • Cardiovascular disease
  • Gastrointestinal motility disorders
  • Hypo- or hyperthyroidism
  • Anemia
  • Renal disease
  • Liver disease, including hepatitis B or C, cholestasis, cirrhotic liver disease, or non-alcoholic fatty liver disease
  • Chronic or acute pancreatitis
  • Diabetes type 1 or 2
  • Insulin resistance
  • Polycystic ovary syndrome

• Food allergies or intolerances to coffee/caffeine/dairy/corn-based cereals.

• Currently taking prescription medication

• Current smoker

• Consumes more than 3 alcoholic beverages per day

• Pregnant or breastfeeding

• Not willing to take their own blood samples with finger sticks

Investigators do not plan to share IPD.

Subjects provided placebo and coffee beverages in a color coded bottles