Plasma insulin and growth hormone during antarctic residence

Circulatory levels of insulin and growth hormone (GH) were estimated in nine tropical euglycemic men in New Delhi and during the first week of every month of stay in Dakshin Gangotri, Antarctica. Prolonged residency in Antarctica did not alter GH levels because mean GH values during Austral summer and Austral winter were not significantly different from the New Delhi values. Compared with GH, the insulin levels during March, April, and June were found to be significantly lower than the New Delhi values. In Antarctica, the insulin levels in March, April, May, June, July, and August were also found to be significantly lower than the December values. This decline in insulin in Antarctica might be important in increasing substrate availability for heat production by facilitating lipolysis and hepatic glucose output.