Should we listen to our clock to prevent type 2 diabetes mellitus?

The circadian clock drives a number of metabolic processes including energy intake, storage and utilization coupled with the sleep/wake cycles. Globally, the increasing prevalence of type 2 diabetes (T2DM) has become a significant international public health concern. In view of the heavy societal burden caused by diabetes, and further, to reduce its growing incidence, it is clearly essential to understand the causes of this disease and to devise more effective strategies for its treatment. Although many factors cause T2DM, this article centers on the role of circadian regulation of metabolism. The correlation between the increased occurrence of T2DM and the ubiquity of modern social pressures such as 24/7 lifestyles as well as nocturnal lighting conditions point strongly to the hypothesis that malfunctioning of circadian controls may be involved in the etiology of the illness. Nocturnal light exposure, unusual timing of food, irregular sleep/wake schedules and traveling between different time zones are some of the factors responsible for improper entrainment of the clock. Recent reports have proposed that strengthening of circadian clock functioning and proper timing of food intake could stabilize glucose homeostasis. This strategy thus represents a chronotherapeutic option for non-pharmaceutical intervention in treating T2DM patients.