Mayo Clinic Health Library

Question

Caffeine: Does it affect blood sugar?

Does caffeine affect blood sugar?

Updated: 04-04-2012

Answer

Caffeine impairs insulin action, but doesn't necessarily affect blood sugar (glucose) levels in young, healthy adults. However, if you have type 2 diabetes, the impact of caffeine on insulin action may be associated with a small, but detectable rise in blood sugar levels, particularly after meals. About 250 milligrams of caffeine — or the equivalent of 2 to 2 1/2 cups (473 to 591 milliliters) of plain, brewed coffee — a day may cause this effect.

If you have type 2 diabetes and you're struggling to control your blood sugar levels, limiting the amount of caffeine in your diet may provide a benefit.

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