Abstract:
The purpose of this study was to compare the effects Cassia cinnamon, cellulose placebo and endurance exercise on an oral glucose tolerance test (OGTT) blood glucose (BG), serum insulin (SI) values, fasting HOMA insulin resistance (HOMA-IR) and Matsuda insulin sensitivity (Mat-ISI). On three separate days, 10 women (22.7 ± 4 years,
BMI of 35.39 ± 5.36) reported to the laboratory for a fasted, venous blood draw.
Participants were administered one of three interventions: 1) 5g of encapsulated placebo;
2) 5g of encapsulated Cassia cinnamon bark; or 3) 50 minutes of treadmill endurance
exercise at a pace sufficient to maintain 70% of the heart rate reserve (HRR). Three
hours after the intervention blood draw was taken, the participants consumed a 75g
glucose solution in 2 minutes. Venous blood draws were taken 30, 60, 90, and 120
minutes after OGTT to determine changes in BG and SI. Statistical analyses included
univariate repeated measures ANOVA, with an a priori contrast, and area under the curve
(AUC) for BG and SI analyses. The total AUC for insulin and glucose, and Mat-ISI were
analyzed with one-way ANOVA. Further analyses of the main effects were performed
by separate one-way ANOVA analyses with a Bonferroni correction. All statistical
procedures were performed using SPSS 16.0 software and a probability level of < .05 was
adopted throughout. The HOMA-IR was not significantly different between the three
interventions (p > 0.05). The Cassia group showed a statistical trend toward a lower
blood glucose value 30 minutes after OGTT (p < .064). The peak blood glucose following OGTT was significantly lower in the Cassia group, as compared to the placebo group (p = .044). The glucose and insulin total AUC and Mat-ISI were not different between the three treatment groups (p > .05). This study provides evidence that Cassia cinnamon may slightly improve post-OGTT blood glucose but does not have any significant effect on insulin response. This study does not provide evidence that moderate endurance exercise modulates post-OGTT insulin response in overweight or obese and sedentary women.
