Reduced frequency of severe hypoglycemia at mild ambient temperatures between 10 and 20 °C: A population-based study under marine west coast climate conditions

Aims To determine the association between ambient temperature and severe hypoglycemia. Methods This was a prospective observational study performed in a prehospital setting. Data from the Emergency Medical Service in Hamburg (Germany) and data from the local weather station were evaluated over a 5-year period. Lowess-regression analysis was conducted to assess the relationship between ambient temperature and frequency of severe hypoglycemia. Additionally, three temperature-ranges were defined in order to compare them with each other with regard to frequency of severe hypoglycemia (< 10 °C vs. 10–20 °C vs. > 20 °C). Results In 2592 patients severe hypoglycemia was diagnosed and treated by emergency physicians (T1DM: n = 829/32%; T2DM: n = 1763/68%). The median age of patients was 64 (57–72 [20–85]) years. Compared to mild temperatures (10–20 °C) the frequency of severe hypoglycemia increased significantly at temperatures above 20 °C (+ 18% (95%-CI: [7%; 22%], p = 0.007) and below 10 °C (+ 15% (95%-CI: [6%; 24%], p < 0.001). Conclusions The results suggest the existence of a “thermal comfort zone” covering a temperature range from 10 to 20 °C in which the frequency of severe hypoglycemia was significantly lower than below 10 °C and above 20 °C.