Introduction: Thyroid hormones (TH) are important determinants of glucose homeostasis,
and in contrast, insulin is the first hormone responsible for glycemic control.
Objective: The objective of the present study was to correlate the levels of insulin and thyroid hormones
in diabetic animals after caffeine consumption associated with physical exercise.
Methods: A total of 48 animals, 60 days old were allocated in eight experimental groups: Control,
Diabetic, Exercise, Diabetes + exercise, Caffeine, Diabetes + Caffeine, Caffeine + Exercise, and Diabetes
+ Exercise + Caffeine. Diabetes model was induced by intraperitoneal administration of 120
mg/kg of alloxan. On the test day, 6 mg/kg of caffeine was administrated 30 minutes before physical
exercise. After, animals performed a 60 minutes’ session of predominantly aerobic exercise, using an
overload of 6% of their body’s weight. Blood has been collected by a caudal puncture to future insulin,
TSH, T3, and T4 analyses.
Results: After caffeine treatment and training, insulin values were higher for the control groups
(231%) when compared to the diabetic groups. A significant increase in plasmatic insulin concentration
was found in caffeine group (95%) and Exercise+Caffeine group (56%) when compared to Control
and Exercise groups. TSH values were increased for Diabetes, Diabetes+Caffeine and Diabetes+
Exercise+Caffeine groups (30%) compared to the other groups. A reduction in T4 values occurred
in the animals of groups Diabetes+Exercise and Diabetes +Caffeine (66%) compared to the
Control group. T3 values were significantly increased for the Diabetes+Exercise group (70%) when
compared to the Diabetes+Exercise+Caffeine group.
Conclusion: Physical exercise and caffeine consumption were able to promote hormonal changes in
diabetic animals after 30 days of training. The study showed a reduction in the serum concentration
of thyroid hormones, but insulin levels were higher.