Epidemiological studies have linked the daily consumption of two to four cups of coffee with a lower risk of type 2 diabetes, according to research published in Food and Chemical Toxicology.

Kusumah J, Gonzalez de Mejia E. Coffee constituents with antiadipogenic and antidiabetic potentials: A narrative review. Food Chem Toxicol. 2022;161:112821.

 

But how does coffee affect people who are already diagnosed and living with diabetes? Although coffee is filled with beneficial plant compounds, it can also be high in caffeine, sugar, and cream, depending on how it is prepared. Patients can easily feel confused by mixed messages about their beloved morning brew.

 

Coffee’s anti-inflammatory properties

 

In the United States, 83% of adults drink coffee. However, not every cup is created equally. In fact, the compounds in coffee can vary quite a bit based on how it’s brewed.

The primary bioactive compounds in coffee include:

• Chlorogenic acid: This is an antioxidant and the most abundant phenolic compound in coffee.

• Diterpene alcohols: These are strong coffee antioxidants, which include cafestol and kahweol.

• Trigonelline: After caffeine, this is the second-highest alkaloid in coffee.

These coffee compounds have established anti-obesity effects, according to the Food and Chemical Toxicology authors, as does caffeine. In addition, studies demonstrate coffee’s ability to lower inflammatory markers like C-reactive protein and leptin, as reported in a 2023 international study in Clinical Nutrition.

Ochoa-Rosales C, van der Schaft N, Braun KVE, et al. C-reactive protein partially mediates the inverse association between coffee consumption and risk of type 2 diabetes: The UK Biobank and the Rotterdam study cohorts. Clinical Nutrition. 2023;42(5):661–669.

 

Coffee intake has also been linked to higher adiponectin levels. Adiponectin is not only anti-inflammatory, but it also boosts insulin sensitivity. Low levels of adiponectin are associated with higher rates of diabetes, obesity, and heart disease.

Less-processed coffee drinks produce the strongest effects, the Clinical Nutrition researchers found, with more significant benefits observed in ground coffee and espresso vs decaf or instant coffee. As a result, the net positive of coffee intake on a progressive and inflammatory disease like diabetes is hard to deny.

 

Coffee’s impact on diabetes complications

 

In the United States, diabetic retinopathy (DR) impacts 40% of those with diabetes, strongly affecting their quality of life.

Cheung N, Mitchell P, Wong TY. Diabetic retinopathy. Lancet. 2010;376(9735):124–136.

Although researchers have yet to confirm a causal relationship, Korean investigators reported that drinking two cups of coffee per day is significantly associated with a lower rate of DR vs drinking no coffee.

Lee HJ, Park JI, Kwon SO, et al. Coffee consumption and diabetic retinopathy in adults with diabetes mellitus. Sci Rep. 2022;12(1):3547.

 

After analyzing data from 1,350 participants, the study investigators noted that, “[R]egardless of the type of coffee, the prevalence of DR tended to decrease with increases in coffee intake of both black coffee and coffee with sugar or cream, adjusted for confounders such as energy intake.”

Nonetheless, clinicians should keep in mind that caffeine may affect people differently. Up to 400 mg of caffeine is considered safe for most adults (the amount in three to four cups of coffee).

Castro RM. Caffeine: Does it affect blood sugar?. Mayo Clinic. April 2022.

 

But for some people with diabetes, caffeine leads to unexpected blood sugar fluctuations that interfere with glycemic control and the action of diabetes medications. In addition, sweetened coffee drinks can be a significant source of carbohydrates and should be accounted for as part of the total diabetes diet.

Myths about diabetes. American Diabetes Association. 2023.

 

For people with diabetes, as for many others, drinking coffee is often more than just a dietary choice. It’s a morning ritual that can be tough to change. Fortunately, coffee is generally something you don’t need to encourage your patients with diabetes to give up. Instead, prioritizing healthy weight loss, physical activity, and medication compliance are likely more worth your while.