Pregnant women who get less than six hours of sleep a night are almost twice as likely to get gestational diabetes (GDM) compared to those who sleep for seven to eight hours, according to researchers from a collaborated Singapore study.

Singapore has one of the highest sleep-deprived rates amongst adults, therefore it is not surprising that it has one of the highest rates of GDM. While it disappears once the baby is born, one in 10 women who had GDM develop Type 2 diabetes within five years of giving birth and three out of four of their babies will be severely obese or diabetic later in life.

Sleep has been identified as one of the factors affecting glucose metabolism and other studies have indicated that short sleep is a risk factor for Type 2 diabetes. The study is novel as it examines the relationship between sleep and GDM in a multi-ethnic Asian population.

Good sleep habits reduce risk of GDM

The GUSTO (Growing Up in Singapore Towards Healthy Outcomes) study recruited 1,247 patients at KK Women's and Children's Hospital (KKH) and the National University Hospital (NUH) between June 2009 and September 2010.

The sleep and glucose levels of the participants were analysed and it was found that 27.3% of pregnant women who slept less than six hours a night developed GDM, compared with 16.8% of those who slept seven to eight hours.

"Our results raise the possibility that good sleep habits could reduce the likelihood of developing hyperglycemia and GDM," said senior author, Associate Professor Joshua Gooley from Duke-NUS Medical School, from the Neuroscience and Behavioural Disorders Programme at Duke-NUS.

The paper however, did not track if the women took any daytime naps, and would not know if it affected their risk of getting GDM. The results are also consistent with findings which show that short sleep is associated with type 2 diabetes in non-pregnant populations and they are also consistent with smaller studies done in Caucasian and African-American pregnant women.

Study contributes to better understanding to counter development of GDM

Indians were found to be at the highest risk with 25% developing GDM, compared with 20.5% among Chinese and 12.4% among Malays. But Professor Gooley said this is due to other factors, possibly genetic, as their sleep patterns were fairly similar.

It is also not known if the shorter hours of sleep were due to hormonal changes, physical discomfort and anxiety during pregnancy, as the researchers did not know the sleep patterns of women prior to their pregnancies.

Nonetheless, the study provides a better understanding of how a potentially serious condition for both pregnant women and their children can be countered, said Dr. Cai Shirong first author of the study from the NUS Yong Loo Lin Medical School and a member of the National University Health System (NUHS). She states that additional studies are needed to assess the contribution of other modifiable lifestyle factors to GDM risk.

"With the recently launched 'War on Diabetes' in Singapore, the importance of healthy sleep habits should be emphasised to doctors and patients, in addition to initiatives that are geared toward improving other lifestyle factors, such as diet and exercise," Professor Gooley adds.

The study is a collaboration between KK Women's and Children's Hospital, the NUHS and the Singapore Institute for Clinical Sciences (SICS), the Agency for Science, Technology and Research (A*STAR). MIMS

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