[1] Blood sugar levels can be affected by some drugs and prior to some glucose tests these medications should be temporarily given up or their dosages should be decreased.
Such drugs may include salicylates (Aspirin), birth control pills, corticosteroids, tricyclic antidepressants, lithium, diuretics and phenytoin.
[medical citation needed] Some foods contain caffeine (coffee, tea, colas, energy drinks etc.).
Blood sugar levels of healthy people are generally not significantly changed by caffeine, but in diabetics caffeine intake may elevate these levels via its ability to stimulate the adrenergic nervous system.
5.6–6 mmol/L (100–109 mg/dL) may indicate prediabetes and oral glucose tolerance test (OGTT) should be offered to high-risk individuals (old people, those with high blood pressure etc.).