Outdoor temperature linked to gestational diabetes risk

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A ‘direct relationship’ has been established between warmer weather and gestational diabetes, researchers say.
Canadian scientists say each 10°C rise in outdoor air temperature is associated with an increased risk of gestational diabetes by up to nine per cent.
The conclusion was made from a study of 555,911 births from 396,828 women, aged 31 years on average, between 2002 and 2014.
The research was carried out by a team from organisations all based in Ontario, including St. Michael’s Hospital, the Institute for Clinical Evaluative Sciences (ICES), Mount Sinai Hospital as well as the University of Toronto.
Extremely cold outdoor temperature levels were defined as an average of minus 10°C or lower, while hot climates were defined as an average of 24°C or above. The participants experienced these temperatures for a total of 30 days before they were tested for gestational diabetes.
Gestational diabetes was present in 4.6 per cent of the women who had experienced the extremely cold temperatures and 7.7 per cent of those who were exposed to the hotter climate had the condition.
Additionally, the researchers discovered that a rise of 10°C increase represented a 1.06 times greater risk of gestational diabetes.
Lead researcher Dr Gillian Booth said: “Many would think that in warmer temperatures, women are outside and more active, which would help limit the weight gain in pregnancy that predisposes a woman to gestational diabetes.
“However, it fits a pattern we expected from new studies showing that cold exposure can improve your sensitivity to insulin, by turning on a protective type of fat called brown adipose tissue.”
Dr Joel Ray, the study’s co-lead author, said: “By further limiting our analysis to pregnancies within the same woman, we controlled for a whole number of factors. Doing so allowed us to eliminate factors like ethnicity, income, physical activity, and eating habits that would differ between two different women.
“Although we studied a single geographical region, our findings are likely to be generalizable to other regions in North America and worldwide. They also warn that, if their findings are correct, this could potentially mean that the worldwide number of GD cases might continue to increase as a consequence of global warming.”
The results have been published in the journal CMAJ.