Larger-than-conventional doses of nonsteroidal antiinflammatory drugs (NSAIDs) are known to lower plasma glucose levels. This phenomenon has raised the questions whether or not NSAIDs in conventional dosage can be used for the treatment of hyperglycemia in patients who have non-insulin-dependent diabetes mellitus and whether or not NSAIDs added to preexistent hypoglycemic drug therapy taken orally may lead to unanticipated hypoglycemia. In this study we evaluated aspirin, sodium salicylate and ibuprofen given in conventional dosage to hyperglycemic patients with adult-onset (type II) diabetes. Half the patients were usually treated for hyperglycemia by means of diet only and half with diet plus hypoglycemic drugs given orally. Significant changes in plasma glucose levels were not seen after the administration of a combination drug containing aspirin and magnesium-aluminum hydroxide (Ascriptin, 650 mg three times a day; glucose change = 236+/-30 to 236+/-31 mg per dl) or sodium salicylate (600 mg three times a day; glucose change=284+/-76 to 273+/-84 mg per dl). A statistically significant but small change was seen with the administration of ibuprofen (600 mg three times a day; glucose change=196+/-60 to 179+/-47 mg per dl) but not when giving ibuprofen (300 mg three times a day; glucose change=267+/-78 to 282+/-60 mg per dl). The results of this study indicate that conventional doses of NSAIDs should not be used for treating hyperglycemia and that, since the additive hypoglycemic effect of NSAIDs in conventional doses was minimal or negligible, they can be used safely for other purposes in diabetic patients taking hypoglycemic drugs orally.