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‘Thermal comfort zone’ reduces frequency of severe hypoglycemia in diabetes

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February 17, 2017

Adults with type 1 and type 2 diabetes living in the Hamburg region of Germany experienced increased incidents of severe hypoglycemia during periods of warmer and cooler temperatures, according to an analysis of weather and patient data.

“Our results suggest the existence of a ‘thermal comfort zone’ covering a temperature range from about 10°C to 20°C in which the frequency of severe hypoglycemia is relatively low,” Mario Hensel, MD, of the department of anesthesiology and intensive care medicine at Park-Klinik Weissensee in Berlin, and colleagues wrote. “This new observation could be of clinical relevance, but the underlying mechanisms of this interesting phenomenon are unknown. Therefore, the discussion must remain largely hypothetical as yet.”

In a prospective, observational study, Hansel and colleagues analyzed electronic medical records from 2,592 patients treated by emergency physicians for severe hypoglycemia (defined by a symptomatic event, such as confusion or loss of consciousness, and confirmed by blood glucose measurement < 2.8 mmol/L) living in the Hamburg region of Germany (mean age, 64 years; 52% men; 68% with type 2 diabetes). Researchers evaluated data from the weather station of Hamburg University of Applied Sciences, obtaining temperature data matched with associated rescue mission data from the Emergency Medical Service in Hamburg (temperature data and health care data were matched with a time-shift of 1 hour). There were no extreme temperatures, such as heat waves, during the observation period. Researchers stratified temperatures by three ranges: low (< 10°C); mild (10-20°C) and high (> 20°C) and used regression analyses to assess the relationship between the ambient temperature and frequency of severe hypoglycemia. Primary endpoint was the difference in frequency of severe hypoglycemia at mild, low or high temperatures.

Within the cohort, 92% of all hypoglycemic events occurred indoors. Compared with periods of mild temperatures, researchers found that the frequency of severe hypoglycemia increased 18% during high temperature periods (95% CI, 7-22) and by 15% during low temperature periods (95% CI, 6-24). The frequency changed slightly when researchers analyzed only outdoor hypoglycemia emergencies, with an observed increase of 21% during high temperatures and a 13% increase during low temperatures.

“As people adapt to their local climates, through physiological, behavioral and cultural adaptation, our findings cannot automatically be transferred to other climate zones,” the researchers wrote. “However, information on local or regional temperature-health relationships can be important in establishing temperature health warning systems.” by Regina Schaffer

Disclosure: The researchers report no relevant financial disclosures.