Friday, February 8, 2008

Caffeine and Diabetes

A new study from Duke University has linked caffeine with a rise in blood sugar levels for those with type 2 diabetes. Dr. James Lane, who lead the study, says that there are two possible reasons for this:

1. Caffeine interferes with the mpovement of glucose from blood to other tissue

2. Caffeine triggers the release of adrenaline, which boosts sugar levels

From personal experience and from discussions with many people who have diabetes, I am inclined to agree with the latter possibility. It explains why so many people with diabetes can drink loose-leaf tea without feeling shaky, but have trouble with coffee and bag tea. As I explained in my article on Caffeine and Tea:

Caffeine is a stimulant that is quickly absorbed into the bloodstream and assimilated into the system. It causes an increase in alertness and energy levels for a short period of time. Its chemical structure is similar to adenosine, which triggers a decrease in cell activity, or a feeing of tiredness. It blocks the brain�s adenosine receptors, tricking them into speeding up activity rather than slowing it down. (They don't recognize the caffeine itself, but react to the LACK of adenosine.) Also, where adenosine would dilate blood vessels, caffeine causes them to constrict. When cell activity speeds up rapidly, the pituitary gland interprets the neural firings as an emergency and releases epinephrine (a.k.a. adrenaline). Adrenaline, in turn, increases your heart rate, blood pressure, and blood sugar levels while dilating your pupils and breathing tubes and tensing your muscles. The result? You feel excited, alert, and ready to go . . . but not for long. Your body responds to the increase in blood sugar by releasing insulin. If your blood sugar levels were rising rapidly (as they tend to do with the rapid absorption of caffeine), then the body tends to overreact. It sends out too much insulin, resulting in LOWER blood sugar levels than BEFORE you consumed the caffeine, as well as the craving for MORE caffeine.

(Added note for blog: Obviously, the wreaks havoc on the blood sugar levels of those with diabetes.)

. . .

In freshly brewed tea, the caffeine binds to the tannins (a.k.a. catechins, a type of polyphenol) and L-theanine when it is brewed. The bond requires more time to metabolize than unbound caffeine, so the absorption of caffeine into the bloodstream is slower and more gradual than it is with coffee and caffeinated sodas. (L-theanine also has some other really cool benefits, like stimulating alpha wave production and GABA formation to induce an alert yet euphoric state.) Meanwhile, the body is absorbing L-theophylline, a naturally occurring substance in tea that produces similar effects to those of caffeine, but with a slower absorption rate. After absorption, caffeine's effects last about 4 hours, L-theophylline, about 8 hours, and the L-theanine, 8-10 hours. This means that you are left with a calm, gentle return to your original energy level. Coffee is different from tea in that its caffeine is quickly absorbed, causing an increase in adrenaline (and stress) levels and resulting in a icky feeling when it wears off (often referred to as a "crash").

Read more on caffeine absorption and tea on Vee Tea.

Anyway, back to the study . . . Dr. Lane also said, "If patients are having trouble controlling their blood glucose and they are coffee drinkers, particularly heavy coffee drinkers, they might want to give it a try to see if it makes a difference to them (to quit drinking coffee)." Read more on the new caffeine and diabetes study on BBC. Have a great weekend!

No comments: