Coffee and Diabetes
Question: Dear Dr. Harris, I was hoping that you could help me. My wife wants me to stop drinking coffee. She says that the caffeine “affects my sugar levels,” and she is worried I will get diabetes. I drink one or two cups of caffeinated coffee about every morning and really like my morning cup o’ joe. What do you guys at SuperfoodsRx think about coffee?
Answer: Recently, my brother-in-law said the same thing to me while I was trying to drink a cup of coffee at a family gathering. He told me that the caffeine would give me diabetes. It seems that there may be a storm brewing against coffee, so I thought I should post this question on the web site.
There are studies that have shown that caffeine causes a brief reduction in glucose tolerance shortly after consumption. Glucose tolerance is the ability of the body to control blood sugar levels after the ingestion of sugar. When you eat a meal with sugar, carbohydrates, or starch, the stomach breaks down these materials to glucose. Glucose is a simple sugar that can be absorbed and used by the body. After the sugar is absorbed it circulates in the bloodstream. High levels of glucose (sugar) in the blood can cause damage to blood vessels so the sugar must be stored for later use. The hormone insulin is released by the pancreas to lower the sugar levels in the blood by storing it in the liver and fat cells.
A reduction in glucose tolerance would mean the body was not responding appropriately to high sugar levels in the bloodstream. Diabetes is an extreme case of reduced glucose tolerance in which the body cannot lower sugar levels without medications or insulin shots. Many physicians, including myself, consider impaired glucose tolerance a form of pre-diabetes that may become diabetes. So, once researchers saw that caffeine briefly reduced glucose tolerance, they sought to prove that coffee caused diabetes. What they found surprised everyone!
Studies over the past five years have shown that drinking caffeinated or decaffeinated coffee can actually reduce the risk of developing diabetes. Some of the studies attributed the decreased risk of diabetes in participants to weight loss which occurred during the studies. Other studies have proposed a difference between the caffeine in coffee and that in caffeine supplements. Ultimately, we still don’t know why, but something in coffee actually lowers the risk of diabetes. Since decaffeinated coffee is also associated with lower risk of developing diabetes, it is likely that phytonutrients in the coffee are preventing the development of diabetes. Coffee contains plant antioxidants and, for many, it is the only source of antioxidants in their day.
Coffee drinking has also been associated with a lower risk of developing gout and Parkinson’s disease. However, recommendations for optimal coffee intake have not been established.
Once again I would like to call for moderation. One to two, eight-ounce cups of coffee a day is reasonable. I recommend decaffeinated coffee because caffeine can raise blood pressure which can lead to heart disease, stroke, and kidney disease. Remember, more is not always better--a study in the Netherlands found an increased risk of developing bladder cancer in men who drank more than seven cups of coffee a day.
I would like to add that tea has a higher antioxidant concentration than coffee. Furthermore, tea consumption has been associated with lower risks for developing many cancers and inflammatory conditions. While coffee is okay, tea is better.
I hope this helps,
Geoffrey R. Harris, M.D.