A survey reported in JAMA showed that drinking coffee reduces risk for developing type II diabetes, but other studies suggest that once you have diabetes, drinking coffee may be unwise.
A report from the Netherlands showed that caffeine in coffee raises blood sugar levels. Diabetics suffer blindness, deafness, heart attacks, strokes, kidney failure, burning foot syndrome and many other serious side effects, and all are caused by a high-rise in blood sugar after meals. Anything that raises blood sugar levels too high increases cell damage in diabetics. This study shows that caffeine raises blood sugar levels by causing the body to put out large amounts of adrenalin that makes cells less responsive to insulin.
When caffeine was removed from the coffee, blood sugar levels did not rise higher than normal. On the basis of this study, diabetics should drink decaffeinated coffee, rather than one with caffeine, in addition to severely restricting sugar-added foods, bakery products, pastas, fruit juices and they should eat root vegetables and fruits only with meals.
Canadian researchers writing in Diabetes Care showed that caffeine significantly reduced insulin sensitivity. In another study in the same journal, scientists from Duke University Medical Center reported that drinking coffee could upset a diabetic’s ability to metabolize sugar.
Blood sugar levels are supposed to rise after you eat. To keep your blood sugar levels from rising too high, your pancreas releases insulin. The researchers found that taking caffeine causes blood sugar and insulin levels to rise even higher after meals. If your blood sugar rises too high, sugar sticks to cells. Once sugar is stuck on a cell membrane, it cannot be released and is converted to a poison called sorbitol which destroys that cell. High levels of insulin constrict arteries to cause heart attacks and act directly on the brain to make you hungry, on your liver to make more fat, and on the fat cells in your belly to pick up that fat. If these studies are confirmed, diabetics will be advised to restrict coffee as well as those foods that cause the highest rise in blood sugar after meals.
Caffeine can decrease insulin sensitivity in humans. Diabetes Care, 2002, Vol 25, Iss 2, pp 364-369. GB Keijzers, BE DeGalan, CJ Tack, P Smits. Smits P, Univ Nijmegen, Med Ctr, Dept Pharmacol Toxicol 233, POB 9101, NL-6500 HB Nijmegen, NETHERLANDS
JAMA, July 6, 2005
Diabetes Care, March 2005