Does Caffeine Raise Blood Glucose Levels?

Can caffeine raise blood sugar levels? If you are a diabetic, is it safe to drink caffeinated coffee, tea, and soft drinks?

A clinical trial at Dartmouth Medical School in New Hampshire found that caffeine may indirectly raise blood sugar levels.

Testing young adults aged 18 to 22, the doctors found that higher levels of insulin after intake of caffeine. The higher level of insulin suggests that their bodies needed more insulin to move the same amount of glucose out of the bloodstream and into cells.

In healthy young adults who don't have diabetes, blood glucose levels stayed the same. In type II diabetics, however, whose blood glucose elevations are caused by insulin resistance, caffeine raises blood glucose levels.

Instant black tea with caffeine, in particular, raises blood glucose levels, but it does not raise them immediately. Instant black tea drinks seem to cause a spike in insulin production right after you drink them, clearing out blood sugar, but they interfere with the release of insulin a couple hours later, allowing you to get a sugar high.

This does not mean, however, all coffee and all tea are bad for diabetics, in fact they can sometimes help prevent diabetes, as you can read here.


Citations:

Bryans JA, Judd PA, Ellis PR. The effect of consuming instant black tea on postprandial plasma glucose and insulin concentrations in healthy humans. J Am Coll Nutr. 2007 Oct;26(5):471-7

MacKenzie T, Comi R, Sluss P, Keisari R, Manwar S, Kim J, Larson R, Baron JA. Metabolic and hormonal effects of caffeine: randomized, double-blind, placebo-controlled crossover trial. 1: Metabolism. 2007 Dec;56(12):1694-8.