Effects of Coffee Consumption on Glucose Metabolism

Coffee and Glucose Metabolism: Clinical, Crossover and Randomized Glucose Disposal Assay Using Stable Isotopes

Epidemiological studies have shown an inverse association between coffee consumption and risk of type 2 diabetes mellitus (T2DM). However the experimental studies that analysed the mechanisms are limited.

This project aims to assess the effects of coffee consumption on glucose metabolism, using stable isotope tracer (13C-glucose) to explain the possible metabolic mechanisms involved on the reduced risk for T2DM.

This is a crossover randomized clinical trial that has been studying 14 male healthy young adults, who were enrolled five treatments: coffee with sugar, coffee without sugar, decaffeinated coffee without sugar and two controls (water with and without sugar).

The stable isotope minimal model protocol with oral glucose administration (Oral Dose Intravenous Label Experiment - ODILE) was performed. The use of ODILE methodology permits separation of the glucose absorbed and removed from the circulation increasing the accuracy and the effectiveness of glucose uptake and insulin sensitivity (Bluck et al., 2006).

Inclusion Criteria:

• Male healthy young adults (18 - 50 years old);
• Body mass index (BMI) between 18.5 - 28.0 kg/m²;
• No weight changes (≥ 5 kg) in the last 3 months;
• Not take any pills/drugs that alter metabolism, appetite and sleep;
• Not have sleep disorders;
• Not have donated blood in the last 3 months;
• Regular breakfast consumption (≥100 kcal ingested up to 2 hours after waking ≥4x/week);
• Being a habitual coffee consumer (≥100mL ≥5x/week).

Exclusion Criteria:

• Diagnosis of anemia, metabolic and heart diseases;
• Previous sudden fainting and convulsions;
• Any drugs and tobacco consumption;
• Consumption of more than 500mg of caffeine / day (5 cups of coffee, tea and cola soft drinks).