THE ROLES OF TIME OF DAY AND SLEEP QUALITY IN MODULATING GLUCOSE REGULATION - CLINICAL IMPLICATIONS

Consistent variations in glucose regulation across the 24-hour cycle a re present in normal subjects. These diurnal variations are altered in various states of impaired glucose tolerance (aging, obesity, diabete s). Changes in insulin secretion, clearance and/or action across the d ay have been demonstrated. Studies in subjects receiving continuous in travenous glucose infusion have shown that major alterations of glucos e tolerance occur during sleep and that sleep quality markedly influen ces glucose utilization. Diurnal variations in glucose tolerance resul t from the alternation of wake and sleep states as well as from intrin sic effects of circadian rhythmicity. The important roles of physiolog ical variations in levels of counterregulatory hormones which are mark edly dependent on sleep (i.e. growth hormone) or circadian rhythmicity (i.e. cortisol) have only begun to be appreciated. The modulatory eff ects of sleep and circadian rhythmicity on glucose regulation may have important clinical implications for the diagnosis and treatment of ab normalities of carbohydrate metabolism.