Regular coffee, which contains caffeine, is shown to impair insulin sensitivity in people with type 2 diabetes. Caffeine has been shown to affect the body’s response to insulin, which is called insulin sensitivity.
People with type 2 diabetes develop an inability either to secrete insulin or to respond to higher blood sugars; the latter situation is known as insulin resistance, and that’s where coffee’s effects need to be considered.
Research published in Diabetes Care in 2002 announced that caffeine decreased insulin sensitivity in healthy male volunteers by 15 percent when compared to placebo. Then, the American Journal of Clinical Nutrition in 2008 published a study, which found that coffee with caffeine significantly impaired insulin sensitivity in healthy men, while decaffeinated coffee did not have the same effect.
Regular high caffeine consumption, over a 4 week period, has been shown to impair insulin sensitivity in people with type 2 diabetes.
In addition, the study also wanted to look specifically at whether caffeine and caffeinated coffee had the same effect when it came to insulin resistance, citing other research that shows moderate coffee intake protects people against type 2 diabetes.
The researchers found that while pure caffeine and caffeinated coffee caused an increase in blood sugar, the effect was less for the coffee. This suggests, they say, that the protective effect of coffee when it comes to type 2 diabetes must be due to other compounds in the coffee.
Having said that, though the researchers found a relationship between higher coffee consumption and lower sensitivity to insulin, they recognised that the rapid transition to having more coffee may have produced an atypical or emphasised response by the body.
So, does regular caffeinated coffee cause insulin resistance?
It would seem to be that the jury’s out, but it is clear that caffeine alone definitely decreases insulin sensitivity. In short, further research is required.
So whilst the caffeine in coffee may hamper insulin sensitivity, other properties in coffee have the opposite effect.
It is therefore believed that decaffeinated coffee may present the best option for people with diabetes as researchers find it includes the benefits of coffee without some of negative effects that are associated with caffeine.