Morning coffee-it is the only way to get the day started for many people all over the world. Recently many articles about coffee have been released in the news. Many people are asking, what’s the story-is coffee a good choice for people trying to prevent diabetes? Is there information about the effects of caffeine and coffee if one has diabetes? We’ll discuss six interesting studies and facts about coffee and caffeine. 

coffee caffeine effects on diabetes management and developing diabetesFact 1: Caffeine and memory - A recent small study carried and published in 2014  at Johns Hopkins University with 73 subjects concluded that as little as 200 milligrams of caffeine enhances a special type of memory called pattern separation for up to 24 hours. When a person distinguishes the differences between two similar items that are not identical, they are exercising pattern discrimination. (1,2,3)

The Mayo Clinic has an interesting graph depicting the amounts of caffeine in many popular drinks

Fact 2: Preventing type 2 diabetes - In both men and women, increased caffeinated and decaffeinated coffee consumption is strongly associated with a reduced risk of developing type 2 diabetes. Researchers at The Harvard School of Public Health just released an evaluation (in 2014) of twenty-eight studies from around the world. The risk of developing diabetes with drinking no coffee or coffee at different amounts was reviewed. Studies took place with a total of 1,109,272 subjects with outcome risk for diabetes type 2 of which there were 45,335 cases of diabetes. The studies followed the participants from 10 months to 20 years. 

There was a 33 percent drop in associated risk of developing type 2 diabetes when six cups of coffee (caffeinated or decaffeinated) was consumed per day.  The researchers did not find significance between the relative risks of developing diabetes by drinking one cup/day caffeinated coffee (9 percent reduction) vs. decaffeinated coffee (6 percent reduction). The risk reduction is significant however, when comparing these individuals to non-coffee drinkers. It was concluded that people who are sensitive to caffeine may enjoy the health benefits of coffee with decaffeinated options. The researchers also stated that drinking coffee should be only one part of a strategy to prevent diabetes. People also need to be mindful of their weight and keep physically active. (4,5)

Fact 3: Coffee drinking and mortality - A large study of more than 40,000 men and women between the ages of 20 and 87 years of age, published in the Mayo Clinic Proceedings (2013), found that people who drank more than 28 cups of coffee per week have a 21 percent increase in mortality from death from all causes. Subjects younger than 55 years of age drinking this amount of coffee, have a 50 percent increase in mortality from all causes. This increased rate of death was not found in people over the age of 55 years. Very importantly however, the researchers could not claim evidence of causality. Subjects who consumed more coffee were also likely to smoke and had lower levels of cardiac fitness. The study team found that the evidence “suggests that heavy coffee drinkers may experience additional mortality risk through potential genetic mechanisms or because of confounding through the deleterious effects of other risk factors with which coffee drinking is associated.” While the research team warns younger people to avoid heavy coffee consumption of more than four cups per day, they also note further studies are needed on the long term effects of coffee consumption. (6)

Fact 4: Athletes with type 1 diabetes - A very small study of adult athletes with type 1 diabetes was presented in 2010 at the American Diabetes Association conference. This study involved five athletes with type 1 diabetes (mean age 38 years of age) who needed multiple, daily injections of insulin. In the study, the athletes had insulin with a meal. Two hours after their meal they consumed five mg/kg of caffeine or a placebo in a drink followed by a 30 minute rest period. This was followed by 40 minutes of measured exercise. The experiment was repeated so all the subjects had data measuring their response to both the placebo and the caffeine to study their need for supplemental glucose to cover the exercise. 

The research team found that on the days the subjects had caffeine, they did not need any supplemental glucose. When the placebo was given, their blood glucose values fell and glucose was needed.

This is a very small study and the research team argues for a large scale study to take place. The team also noted that the amount of caffeine used was high. They plan another study with a lower dose of caffeine. The authors mentioned that when a person with type 1 diabetes has unplanned exercise and cannot reduce their insulin dose, caffeine may reduce the extra calories needed to treat hypoglycemia. Please note again, more research needs to be done in this intriguing area. (7)

Fact 5: Coffee and type 2 diabetes - A small study of brewed coffee drinkers (five men and five women) mean age 63 years with type 2 diabetes was conducted at Duke University (2007) to evaluate the effect of caffeine on blood glucose. The participants' diabetes was managed with diet, exercise and oral agents. Their A1c values were approximately 6.4 percent. None of the participants required insulin as a medication, smoked or used psychotropic medications. The study compared the effects of 500 mg/day of caffeine with a cross over placebo control conducted on different days. The dose of caffeine or placebo was given divided between breakfast and lunch. A continuous blood glucose monitoring device was worn on study days. The results showed that when the participants consumed caffeine, their daytime blood glucose concentrations were higher and they had an exaggerated postprandial glucose response. It was also interesting to note that the subjects exhibited reduced overnight glucose levels when the caffeine was given compared to the placebo.  Future studies need to be done. (8)

Fact 6: Coffee consumption during pregnancy - The American Association of Clinical Endocrinologists recommends pregnant women consume, no more than 300 mg of caffeine (approximately three cups of coffee) per day. This amount is generally not associated with miscarriage and stillbirth which has an association with consuming caffeine in large quantities. (9)

These studies are interesting to read. As you can see, more research needs to be performed on coffee consumption in people with diabetes. Most studies done with people diagnosed with diabetes are small. Make sure to ask your medical team if coffee is for you and if you have any limits for your particular case. Negative effects from drinking coffee can include sleeplessness, nervousness, a fast heart rate, and muscle tremors. (10) For people with diabetes, from the studies listed it can also cause changes in your blood glucose.