Effects of lithium, nortriptyline and dexamethasone on insulin sensitivity

The effects of lithium, dexamethasone, nortriptyline and their combinations on insulin sensitivity, expressed as a drop of plasma glucose in response to insulin challenge, were investigated in healthy volunteers. Short-term (three weeks) lithium treatment did not appear to exert any influence on the insulin sensitivity. Dexamethasone administered alone (2 mg given 57 hours prior to the test) had no effect on the insulin sensitivity of drug-free healthy subjects. However, after three weeks of lithium treatment the dexamethasone premedication resulted in slight flattening of glucose response to insulin in the same persons. Nortriptyline administered for three weeks to healthy volunteers, pretreated with dexamethasone, increased insulin sensitivity. These findings may have clinical implications regarding the treatment of depressed diabetic patients, and may provide information about the regulation of insulin sensitivity.