London : People, especially women, who mix day and night shifts are at greater risk of developing type 2 diabetes, a new Harvard study has claimed.

People who rotate through shifts for just a few years are more to susceptible as they are more likely to suffer from disrupted eating patterns and sleep deprivation, which in turn leads to weight gain and diabetes.

Type 2 diabetes can lead to a number of serious health problems including heart disease, stroke, kidney failure and blindness, the researchers said.

"The increased risk is not huge, but it''s substantial and can have important public health implications given that almost one-fifth of the workforce is on some kind of rotating night shift," Dr Frank Hu, a Harvard University professor who led the study, was quoted as saying by the Daily Mail.

According to Dr Hu, working irregular hours can disrupt the body''s circadian rhythms - also known as the body clock -- which plays a critical role in maintaining healthy blood-sugar metabolism.

The study, published in the journal PLoS Medicine, was based on 177,184 women, aged between 42 and 67 years, who were followed for two decades as part of a Nurse''s Health Study.

Those who worked at least three nights per month, in addition to day and evening hours were considered rotating night-shift workers.

It was found that the increase in type 2 diabetes risk associated with night shift work ranged from five per cent in nurses who''d worked that schedule for one or two years to 58 per cent in those who had done so for at least 20 years.

The findings supported past research which highlighted that sleep deprivation can lead to insulin resistance and rising blood-sugar levels -- both precursors of diabetes.