Caffeine Impairs Sugar Metabolism

Diet and Nutrition
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Caffeine Impairs Sugar Metabolism

Caffeine intake makes insulin more resistant to changes in blood sugar levels, Canadian researchers report. This effect was observed both in patients with and those without diabetes and could not be reversed with regular exercise or weight.

But before you throw away your coffee mug – these results may not apply to the popular caffeinated beverage, the investigators note. In fact, previous research has suggested that drinking coffee may cut the risk of diabetes.

When sugar levels in the blood get too high, insulin is released, which brings the levels back down. With insulin resistance, also known as decreased insulin sensitivity, sugar levels need to get much higher before insulin release is triggered. Over time, this resistance can cause problems and lead to diabetes.

“Through mechanisms that have yet to be firmly established, caffeine attenuates any of the beneficial effects of exercise or weight loss on insulin resistance,” Dr. Robert Ross of Queens University in Kingston, Ontario, told Reuters Health.

While the clinical implications remain unclear, Ross added, the findings are a “red flag” for doctors and are particularly important for obese patients and those with diabetes.

Ross and his team evaluated sugar metabolism in 23 men before and after a three-month exercise program. Before and during the exercise program, the men were given caffeine or inactive “placebo.” The subjects included eight sedentary lean men, seven obese men with type 2 diabetes, and eight obese men without diabetes.

Before the exercise program, caffeine reduced insulin sensitivity by 33 percent in the lean and obese men and 37 percent in the men with diabetes compared to placebo. After the exercise program, insulin sensitivity fell 23 percent after caffeine intake in the lean men, 26 percent in the obese men, and 36 percent in the diabetic men.

Comparison of the two study phases, showed that exercise did not improve insulin resistance related to caffeine intake.

The findings, published in the medical journal Diabetes Care, seem to contradict recent reports that coffee intake may cut the risk of diabetes, Ross noted. However, coffee contains several other substances that may affect sugar metabolism, such as antioxidants, potassium and magnesium. “When you give somebody caffeine without all of the other substances that are in coffee you have a very different situation,” he added.

SOURCE: Diabetes Care, March 2005.

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Yeah, I read that too. Does it apply mostly to diabetics, or to the general population. I am a caffeine junkie…

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Anyone know the dosage of caffeine used in the study?

I remember a JB article about this premise, sometime ago.

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Coffee consumption and risk for type 2 diabetes mellitus.

Salazar-Martinez E, Willett WC, Ascherio A, Manson JE, Leitzmann MF, Stampfer MJ, Hu FB.

Harvard School of Public Health, Channing Laboratory, Harvard Medical School, and Brigham and Women’s Hospital, Boston, Massachusetts 02215, USA.

BACKGROUND: In small, short-term studies, acute administration of caffeine decreases insulin sensitivity and impairs glucose tolerance. OBJECTIVE: To examine the long-term relationship between consumption of coffee and other caffeinated beverages and incidence of type 2 diabetes mellitus. DESIGN: Prospective cohort study. SETTING: The Nurses’ Health Study and Health Professionals’ Follow-up Study. PARTICIPANTS: The authors followed 41 934 men from 1986 to 1998 and 84 276 women from 1980 to 1998. These participants did not have diabetes, cancer, or cardiovascular disease at baseline. MEASUREMENTS: Coffee consumption was assessed every 2 to 4 years through validated questionnaires. RESULTS: The authors documented 1333 new cases of type 2 diabetes in men and 4085 new cases in women. The authors found an inverse association between coffee intake and type 2 diabetes after adjustment for age, body mass index, and other risk factors. The multivariate relative risks for diabetes according to regular coffee consumption categories (0, <1, 1 to 3, 4 to 5, or > or =6 cups per day) in men were 1.00, 0.98, 0.93, 0.71, and 0.46 (95% CI, 0.26 to 0.82; P = 0.007 for trend), respectively. The corresponding multivariate relative risks in women were 1.00, 1.16, 0.99, 0.70, and 0.71 (CI, 0.56 to 0.89; P < 0.001 for trend), respectively. For decaffeinated coffee, the multivariate relative risks comparing persons who drank 4 cups or more per day with nondrinkers were 0.74 (CI, 0.48 to 1.12) for men and 0.85 (CI, 0.61 to 1.17) for women. Total caffeine intake from coffee and other sources was associated with a statistically significantly lower risk for diabetes in both men and women. CONCLUSIONS: These data suggest that long-term coffee consumption is associated with a statistically significantly lower risk for type 2 diabetes.

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Thanks for posting both findings.

Concerning the later, long-term study, it appears caffeine has less to do with preventing Type 2 diabetes when it comes to coffee. Rather it appears that other nutrients/chemicals contribute in a greater effect, at least in men. Looking at the results in men that consumed either decaf or regular coffee, the chances were almost equally lowered (.71 for regular coffee and .74 for decaf) when drinking 4 cups per day. However, in women, it appears as though drinking caffeinated coffee significantly lowered their risk vs. decaf (.70 compared to .85) at the 4 cup per day level.

Another interesting point, according to this study, women who drank between 0 and 1 cups of caffeinated coffee had an INCREASED risk of developing diabetes over those that drank none at all (1.16 compared to 1.00)! Ouch!

And finally, the study mentioned that caffeine from other sources helped prevent type 2 diabetes, yet it didn’t include the data to support such claims. It would help to know just how much total caffeine, both from coffee and from other sources, helped to blunt the on-set of diabetes.

TopSirloin

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[quote]TopSirloin wrote:

Looking at the results in men that consumed either decaf or regular coffee, the chances were almost equally lowered (.71 for regular coffee and .74 for decaf) when drinking 4 cups per day. However, in women, it appears as though drinking caffeinated coffee significantly lowered their risk vs. decaf (.70 compared to .85) at the 4 cup per day level.[/quote]

you will also note that neither of the decaffinated groups reached statistical significance, where as the caffinated coffee groups did.