New York, Nov 14 (IANS): Women, especially those after menopause, not sleeping adequately may be at risk of diabetes, according to a study.

The findings led by Columbia University researchers found that sleep loss of 90 minutes for six weeks increased fasting insulin levels by over 12 per cent overall.

The effect was even more pronounced in postmenopausal women -- more than 15 per cent.

The recommended amount of sleep for optimal health is between seven and nine hours per night.

The study, published in the journal Diabetes Care, is the first to show that a mild sleep deficit, maintained for six weeks, causes changes in thebody that raises the risk of developing diabetes in women. Poor sleep is known to have a greater impact on women's cardiometabolic health than men's.

"Throughout their lifespan, women face many changes in their sleep habits due to childbearing, child-rearing, and menopause," said Marie-Pierre St-Onge, Associate Professor of nutritional medicine at the varsity's Vagelos College of Physicians and Surgeons.

"And more women than men have the perception they aren't getting enough sleep."

For the study, the researchers enrolled 38 healthy women, including 11 postmenopausal women, who routinely slept at least seven hours each night.

In the study, the participants underwent two study phases in random order. In one phase, they were asked to maintain their adequate sleep; in the other, they were asked to delay their bedtime for an hour and a half, shortening their total sleep time to around six hours.

Each of these phases lasted for six weeks.

Insulin resistance increased by nearly 15 per centoverall and by more than 20 per centamong postmenopausal women. Average blood sugar levels remained stable for all participants throughout the study.

"Over a longer period of time, ongoing stress on insulin-producing cells could cause them to fail, eventually leading to type 2 diabetes," St-Onge said.

Although increased abdominal fat is a key driver of insulin resistance, the researchers found that the effects of sleep loss on insulin resistance were not due to increases in fat.

"The fact that we saw these results independent of any changes in body fat, which is a known risk factor for type 2 diabetes, speaks to the impact of mild sleep reduction on insulin-producing cells and metabolism," St-Onge said.