Does Black Coffee Affect Blood Sugar?

Cup of coffee
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Black coffee can affect your blood sugar, causing it to rise. For some people, mainly people with diabetes, this can be a real problem. Controlling your blood sugar may mean you have to cut down on coffee intake. But although this effect is seen in people with diabetes, there is evidence that suggests drinking coffee can help reduce the risk of developing type 2 diabetes.


Effect on Diabetes

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A study published in "Diabetes Care" in 2007 looked at the effects of black coffee on blood glucose levels. Ten individuals with well-controlled type 2 diabetes, who habitually drank coffee, received either a 500 mg capsule of caffeine or a placebo. Those taking the caffeine had higher overall glucose levels and higher postprandial glucose levels than the control participants. The researchers say the mechanism behind caffeine and glucose levels may involve the hormonal regulation of uptake. They suggest that the presence of caffeine increases the hormone epinephrine, which reduces glucose metabolism. Another speculation concerns control of the brain's regulation of glucose uptake -- caffeine affects certain receptors inside the brain that might inhibit glucose clearance into the cells.

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Effect on People Without Diabetes

Caffeine intake may actually help prevent the development of type 2 diabetes, explains Science Daily. People without diabetes are able to make up for the rise in glucose through the production of extra insulin. Insulin is the hormone that drives glucose clearance, and the body just needs to pump a little more out to take care of the effects of caffeine on blood glucose.



A habitual coffee drinker may be wondering how much caffeine will cause an effect. About 250 mg of daily caffeine can cause blood glucose disruption. This is the equivalent of 2 to 2.5 cups of black coffee per day. If you need to reduce the impact black coffee has on your blood glucose, cut down on your daily intake.

Possible Preventive Effect

If you do not have diabetes, black coffee may be helpful in preventing this chronic condition, according to a 2011 study from UCLA. Researchers identified a link between coffee consumption and the amount of sex hormone-binding globulin, SHBG, in the blood. People with low amounts of SHBG in the bloodstream are more likely to develop type 2 diabetes. Drinking caffeinated coffee influences the levels of SHBG in the blood. Researchers studied 359 people newly diagnosed with diabetes and 359 subjects without diabetes to analyze coffee drinking habits and levels of SHBG. The subjects who drank at least four cups of coffee per day had higher levels of SHBG and were 56 percent less likely to be diagnosed with diabetes.




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