What you should know about coffee and diabetes

Diabetes (or diabetes mellitus) is a disease that impairs the body’s ability to process blood sugar (or blood glucose). Diet plays an important role in the management of all types of diabetes as eating a healthy diet can help to keep blood sugar in the target range. 

It’s important for those with diabetes to be aware of how certain foods and drinks affect their blood sugar. So, what about the cup of joe that many of us reach for in the morning to help get us going? How does coffee intake affect diabetes? What are the effects of caffeine on insulin?

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According to the Mayo Clinic, caffeine consumption could have an impact on insulin action for all types of diabetes (Type 1 diabetes, Type 2 diabetes, gestational diabetes, and prediabetes) as it may result in higher or lower blood sugar levels. But what is it about coffee that could actually help with diabetes prevention?

Coffee and Type 2 diabetes prevention

Coffee drinkers will be happy to know that drinking their favorite coffee concoction could have an added benefit for their health. “Data suggests that coffee consumption reduces the risk of developing Type 2 diabetes,” says Aleem Kanji, MD, a board-certified endocrinologist at Ethos Endocrinology in Houston, Texas. 

One systematic review that looked at 28 studies (involving more than 1 million participants) found that “both caffeinated and decaffeinated coffee was associated with reduced diabetes risk.”

Coffee contains antioxidants—molecules that may help to prevent or delay some types of cell damage. A diet high in antioxidants may lower risk of diseases such as cardiovascular disease and diabetes. Coffee also contains minerals such as magnesium (albeit a small amount); which has been shown to help the body break down sugar. 

The news is promising, but more research needs to be done before we know just how much coffee correlates with a lower risk of Type 2 diabetes. “Currently, there is no formal recommendation for coffee consumption as a method of reducing the risk of Type 2 diabetes, and thus, a certain number of cups can’t be recommended,” Dr. Kanji says. “However, currently available studies suggest three to four cups per day resulting in reduced risk.”

Is it okay to drink coffee if you have diabetes?

Those living with diabetes don’t have to go without their favorite coffee drink, but how much caffeine they consume could matter—as does the amount of sweeteners that are added.  

“Research has mixed findings on the effect of coffee, insulin levels, and blood sugar control,” says Michelle Routhenstein, MS, RD, a certified diabetes educator and owner of entirelynourished.com. “Some studies show that coffee can cause insulin insensitivity, meaning it impairs the body’s ability to utilize blood sugar and place it into the cell where it belongs, leading to high blood sugar readings. While other studies show that coffee over a long-term period may actually help with insulin levels.” 

According to Routhenstein, an average cup of coffee contains about 70 to 350 mg of chlorogenic acid, a polyphenol that may cause a reduction in blood sugar by inhibiting carbohydrate digestion while also stimulating insulin secretion.

It appears that regular coffee can have an effect on insulin, but the impact varies based on the individual and their overall daily caffeine consumption. 

“Some studies suggest improved insulin sensitivity and blood glucose response when insulin and blood sugar markers are measured one and two hours after consumption,” Dr. Kanji says. “There are also a few studies that show worsened glucose metabolism, especially after caffeinated coffee. One study testing 126 people with four cups of caffeinated coffee over 24 weeks found no significant effect on insulin sensitivity.”

The bottom line is that coffee affects people differently and those with diabetes should consult with their healthcare provider or diabetes educator regarding their consumption of coffee and caffeine intake and monitor how it is affecting their blood sugar levels. 

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Healthy coffee tips and alternatives for those with diabetes

Those with diabetes who are concerned about coffee’s impact on their blood sugar can reduce the amount they consume, forgo adding sweeteners, switch to decaf coffee, or drink an alternative to coffee such as tea, which contains the same helpful polyphenols as coffee.   

While there may be some health benefits of coffee, it’s important to remember that sweetening coffee with cream, sugar, and artificial sweeteners can increase a person’s risk of diabetes and worsen blood glucose levels in people with diabetes. The same goes for coffee alternatives such as tea. 

“What we put into the coffee matters,” Routhenstein says. “Some creamers are a rich source of saturated fat that can clog the arteries and lead to heart disease; excess sugar can also lead to a spike in blood sugar levels and inflammation in the blood vessels, and artificial sweeteners can negatively impact the gut microbiome, which can also lead to other chronic diseases.”

Saturated fat and excess sugar can also contribute to weight gain, and obesity is a risk factor for prediabetes and Type 2 diabetes.

The beneficial effects of coffee could be outweighed by the potential to exacerbate some diabetes symptoms. For example, caffeine is a diuretic, which can increase the frequency of urination, and frequent urination is already a symptom of diabetes. 

Fatigue is another diabetes symptom. Coffee or other beverages with a high caffeine content could give you a temporary boost, but result in a crash after the caffeine wears off.

Another factor to be aware of is how coffee could interact with medications used to treat diabetes. Because coffee may increase blood sugar, the diabetes medications used to lower blood sugar may be less effective. 

The bottom line? “If you enjoy coffee, stick to one to two cups daily (unless you have medical reasons to avoid it) and limit the unnecessary additives,” Routhenstein recommends.