Drinking Coffee May Reduce Diabetes Risk by 29 Percent

Written by Dr. Joseph Mercola Fact Checked

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Story at-a-glance -

  • A meta-analysis of 30 studies involving more than 10 years of research suggests habitual coffee consumption may slash your risk of developing Type 2 diabetes by as much as 29 percent
  • While the results suggest caffeinated and decaffeinated coffee have favorable metabolic effects, Type 2 diabetes risk reduction was more strongly associated with caffeinated brews
  • Researchers assert your risk of Type 2 diabetes can decrease by 6 percent for each cup-per-day increase in your coffee intake
  • Organic, black coffee is the healthiest coffee for you and most definitely a better source of caffeine than soda or energy drinks

After conducting a systematic review of more than 10 years of research, scientists from Sweden’s Karolinska Institutet have concluded habitual coffee consumption may slash your risk of developing Type 2 diabetes by as much as 29 percent.1

Notably, while the results suggest both caffeinated and decaffeinated coffee have favorable metabolic effects, the risk reduction associated with new-onset Type 2 diabetes appears to be stronger with caffeinated coffee. If you are looking for another reason to enjoy a cup of organic coffee, these findings may be of interest to you.

A Few Facts About Coffee

Coffee has long been one of the most widely consumed beverages globally, playing a central role in diverse cultures around the world. Since its discovery more than 1,000 years ago in the region now known as Ethiopia, coffee has taken center stage as a social icon.

You might invite a friend or coworker to “meet for coffee” or join you for a “coffee break.” Below are some facts about this popular drink, as presented by the European Coffee Federation:2

  • An estimated 2 billion cups of coffee are consumed around the world every day
  • Coffee is one of the most valuable products in world trade and its cultivation, marketing, processing, trading and transportation provide employment for millions of people globally
  • Coffee is grown in about 70 countries, with small operations producing approximately 80 percent of the world’s coffee supply
  • Brazil is the largest producer of coffee, contributing 40 percent of the world’s supply, followed by Vietnam with 16 percent

About this ubiquitous beverage, the European Coffee Federation says,3 “Coffee … is one of the most extensively researched components in the diet. Taken overall, the research indicates that moderate coffee consumption can be part of a healthy, balanced diet for the general adult population and may even confer health benefits.”4

Rates of Type 2 Diabetes Continue to Rise

The global rates of diabetes — a chronic disease that arises when your pancreas does not produce enough insulin or your body cannot effectively use the insulin it produces — continue to skyrocket. According to the World Health Organization (WHO), the number of people with diabetes increased from 108 million in 1980 to 422 million in 2014.5

The WHO notes the prevalence of diabetes, which is a major cause of blindness, heart attacks, lower limb amputation, kidney failure and stroke, has been rising more rapidly in low- and middle-income countries. They estimate diabetes was the seventh leading cause of death in 2016, and its prevalence has been steadily increasing for the past 30 years.6

According to a report by the U.S. Centers for Disease Control and Prevention (CDC),7 around 30.3 million Americans had diabetes in 2015, with 7.2 million of those cases going undiagnosed.

They note Type 2 diabetes is the most common form of the disease, accounting for 90 to 95 percent of all cases. With increasing numbers of people suffering from diabetes, researchers are investigating every possible prevention strategy, including the consumption of coffee.

Coffee Drinking Found to Slash Your Risk of Type 2 Diabetes

Given the skyrocketing rates of diabetes worldwide, news of a positive association between coffee drinking and the potential lower risk of Type 2 diabetes is noteworthy.

Based on a meta-analysis of 30 prospective studies conducted between 2002 and 2015, researchers from Sweden’s Karolinska Institutet suggest coffee consumption is inversely associated with Type 2 diabetes risk.8

The analysis, which pooled data from nearly 1.2 million participants, featured 53,018 Type 2 diabetes cases. The pair of researchers found the risk of Type 2 diabetes was 29 percent less within the highest coffee consumption group (median consumption was 5 cups per day) as compared to the lowest coffee consumption group (median consumption was zero cups per day).

Beyond that, they suggest the risk of Type 2 diabetes decreased by 6 percent for each cup-per-day increase in coffee consumption. Results were similar for caffeinated versus decaffeinated coffee. The study authors stated:9

“Available evidence indicates that coffee consumption is inversely associated with risk of Type 2 diabetes. Possible mechanisms behind this association include thermogenic, antioxidative and anti-inflammatory effects; modulation of adenosine receptor signaling; and microbiome content and diversity.”

The Health Benefits of Coffee Compounds Like Cafestol

Research continues to call out certain compounds in coffee that are responsible for its health-boosting properties. A 2017 study published in the Journal of Natural Products,10 for example, suggests cafestol, a bioactive compound found in coffee, improved Type 2 diabetes markers in research involving lab mice fed a daily dose of the compound. The results were summarized as follows:11,12

  • Groups fed either 0.4 or 1.1 milligrams of cafestol experienced a 28 to 30 percent reduction in blood glucose levels, compared to the control group
  • Mice fed the higher dose of cafestol reflected a 42 percent improvement in insulin sensitivity, compared to the control group
  • Mice fed the higher dose of cafestol showed a 20 percent reduction in fasting glucagon, the hormone responsible for increasing blood glucose levels

At the end of the 10-week study period, scientists isolated islets of Langerhans — the pancreatic cells that normally produce insulin — from each group of mice. As compared to the control group, they found the islets isolated from mice fed cafestol were associated with a 75 to 87 percent increase in insulin production.

About the outcomes, the study authors stated, “Our results show cafestol possesses antidiabetic properties. Consequently, cafestol may contribute to the reduced risk of developing Type 2 diabetes in coffee consumers and has a potential role as an antidiabetic drug.”13

About the many beneficial compounds found in coffee, the team from the Karolinska Institutet stated:14

“Numerous bioactive components in coffee have been proposed to contribute to the associated favorable metabolic effects, including caffeine, phenolics … lignans, trigonelline, N-methylpyridinium, minerals and vitamins … proteins and lipids in special diterpenes (e.g., cafestol and kahweol).

Many of these compounds may play a role in regulation of insulin and glucose and thus influence the development or progression of Type 2 diabetes.”

Increasing Your Coffee Intake by Just 1 Cup a Day Can Make a Big Difference

A 2014 study published in the journal Diabetologia15 suggests increasing your coffee intake may reduce your risk of Type 2 diabetes, whereas an increase in tea consumption had no effect on diabetes risk. The researchers examined associations among changes in coffee and tea consumption and the risk of Type 2 diabetes as evaluated during a four-year study period.

Data was provided from 48,464 women involved in the Nurses' Health Study (1986 to 2006), 47,510 women in Nurses' Health Study II (1991 to 2007) and 27,759 men in the Health Professionals Follow-up Study (1986 to 2006).

Diet was assessed every four years using a validated food-frequency questionnaire, and self-reported cases of Type 2 diabetes were validated through supplementary questionnaires.

In all three cohorts, the researchers collected detailed information on diet, lifestyle, medical conditions and other chronic diseases every two to four years for more than 20 years. Having documented 7,269 cases of Type 2 diabetes, the scientists found:

  • Participants who increased their coffee consumption by more than 1 cup per day (median change = 1.69 cups per day) over a four-year period had an 11 percent lower risk of Type 2 diabetes in the subsequent four years compared with those who made no changes in their consumption
  • Participants who decreased their coffee intake by more than 1 cup per day (median change was minus 2 cups per day) experienced a 17 percent higher risk of Type 2 diabetes
  • Changes in tea consumption were not associated with Type 2 diabetes risk

“Our findings confirm those of previous studies that showed higher coffee consumption was associated with lower Type 2 diabetes risk,” said lead author Shilpa Bhupathiraju, research fellow in the department of nutrition at Harvard School of Public Health (HSPH). “Most importantly, they provide new evidence that changes in [a] coffee-consumption habit can affect Type 2 diabetes risk in a relatively short period of time.”16

Added senior author Dr. Frank Hu, chair of the department of nutrition at HSPH, “These findings further demonstrate that, for most people, coffee may have health benefits, but coffee is only one of many factors that influence diabetes risk. More importantly, individuals should watch their weight and be physically active.”17

Health Benefits of Coffee Extend From Your Heart to Your Brain

Research presented at the American Heart Association's Scientific Sessions 2017 found that compared to noncoffee drinkers, coffee drinkers were observed to have a 7 percent lower risk of heart failure and an 8 percent lower risk of stroke for each additional cup of coffee consumed per week.18

Authors of a 2017 meta-analysis published in BMJ noted coffee consumption of 3 to 4 cups a day versus none had a “nonlinear association” to reduce your risk of:19

  • All-cause mortality by 11 percent
  • Cardiovascular mortality by 19 percent
  • Cardiovascular disease by 15 percent

In addition, high versus low coffee consumption was associated with an 18 percent lower risk of cancer. The scientists added, “Consumption was also associated with a lower risk of several specific cancers and neurological, metabolic and liver conditions.”20

As noted in the video above, research published in PLOS Biology21 indicates the consumption of 4 cups of coffee a day may provide sufficient caffeine to help protect and repair your heart muscle, as well as protect your cells against heart attack damage better than consuming no caffeine.

As for your brain health, increased coffee (and tea) consumption was linked to a lower risk of glioma brain tumor, such that people in the top category of coffee consumption were 91 percent less likely to have glioma compared with those in the bottom category.22

According to a study published in the journal Clinical Nutrition, drinking 1 to 2 cups of coffee daily, as compared to drinking less than 1 cup, was associated with a 12 percent lower risk of cognitive disorders, including Alzheimer's disease, other forms of dementia, cognitive decline and cognitive impairment.23

Organic, Black Coffee Is Best for You; Skip the Soda

Because conventional coffee is heavily sprayed with pesticides, you’ll want to choose organic, shade-grown varieties. For the best cup of coffee, I advise you skip health-busting additives like sugar, nondairy creamer and artificial sweeteners. At least one study indicated the addition of milk significantly reduced the antioxidant content of coffee.24

As often as possible, you'll also want to purchase whole-bean coffee and grind it yourself to prevent rancidity. Preground coffee may be rancid by the time you drink it. Also, if you drink decaffeinated coffee, be sure the decaffeination process doesn't involve chemicals. 

If you are pregnant, you would be wise to avoid caffeine from coffee and other sources because it has been shown to increase your chances of prolonging gestation and having a baby with low birth weight. For more information about coffee and pregnancy, check out my article “Why Therapeutic Benefits of Coffee Do NOT Apply to Pregnant Women.”

For most people, a few cups of organic coffee a day can deliver a number of health-promoting benefits, including lowering your risk of Type 2 diabetes. If you need a morning energy boost, I recommend you choose organic coffee over energy drinks and soda. Given the massive amounts of sugar, including high fructose corn syrup, found in it, I highly recommend you “Give Up Soda.”