Effects of Coffee Roasting on Blood Sugar Levels in Healthy Humans

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