Results were obtained by measuring blood sugar levels on the patients after taking caffeine and after taking placebo.
Subjects’ nutritional intake was regulated using coded packets of food and took either caffeine tablets or a placebo after breakfast and lunch. The dosage of caffeine was 500mg a day.
Tests revealed daytime glucose levels of 8 mmol/l with caffeine and 7.4 mmol/l with placebo.
Caffeine elevated average glucose concentrations following breakfast (8.7 mmol/l vs 8 mmol/l) lunch (7.8 mmol/l vs 6.8 mmol/l) and dinner (8.6 vs 6.8mmol/l).
Authors concluded: ‘Repeated epidodes of elevated glucose resulting from daily consumption of caffeinated beverages could impair clinical efforts aimed at glucose control and increase risk of diabetes complications.’
Diabetes Care (2008) 31: 1-2