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Thirty four healthy young male subjects performed symptom limited exercise on Bruce protocol on treadmill machine. Hyperventilation induced labile repolarisation ST-T abnormalities were observed in 2 whereas exercise induced ST changes (upsloping ST depression in 4 and horizontal ST depression in 1) were observed in 5 additional candidates. Changes were unaccompanied by symptoms or signs and quickly reverted back to normal within 30 sec. of cessation of exercise and hence were 'probable false positives'. Sixty-eight age and sex matched volunteers (including former 34) when exercised on Master's stepper, failed to reveal any change probably due to the lack of continuous ECG monitoring device.

Experimental studies on pinealectomized animals and in vitro studies using pancreatic tissue, have indicated that the pineal gland has a suppressive effect on the pancreatic B cells which secrete insulin. In this study, melatonin, was injected into rabbits and a statistically significant decrease in glucose tolerance was noted. The effect of melatonin in influencing the circadian rhythm of blood glucose was also studied in rabbits. Results showed that melatonin influences the circadian rhythm leading to a shift in the occurrence of minimum levels from 16.00 hr to 04.00 hr (next day) during fasting and from 16.00 hr to 20.00 hr during feeding. Also melatonin treatment lead to a statistically significant rise in blood glucose levels. It is probable that melatonin administration reduces glucose tolerance and influences the blood glucose circadian rhythm mainly through its effects on insulin release by pancreatic B cells.

Light and exhaustive ergometric exercise in untrained male and female medical students in the age group 18-21 years resulted in significant lowering of the blood sugar, cholesterol and pH. Females exhibited hypoglycemia of slightly greater magnitude as compared to male subjects and during both the exercises, however, such sex differences were not observed for changes in cholesterol and pH.