For many people the day starts with coffee. After a diabetes diagnosis it is natural to wonder whether that cup is a problem, or, if you have read the headlines, whether it might even help.

There are really two questions here. One is about the coffee itself. The other is about what goes into it. This article takes them one at a time, and keeps apart what research found in people without diabetes from what it found in people who already have it.

Black coffee and what you add

Here is plain brewed coffee next to a latte, each at one medium cup as USDA FoodData Central measures it:

Plain brewed coffee shows almost no carbohydrate. The latte shows a good deal more, and nearly all of it comes from the milk. The coffee is the same; the cup is not.

Flavored and ready-to-drink coffees go further, because sugar or syrup is added on top of the milk:

Compare these cards with the plain latte above. The difference is the sweetening. NIDDK lists "flavored coffee" among the sweet drinks, next to soda and juice, and lists unsweetened coffee among the drinks with little or no added sugar.

Sugar and creamer added at home count too. Spoonfuls of sugar, flavored creamers and sweet syrups all add carbohydrate, and several cups a day add up. Creamers have their own food pages here; set the amount to what you actually pour, since a splash is much less than the default cup. On a bottle or tub, the Nutrition Facts label gives the carbohydrate per serving. Our article on reading nutrition labels for carbs explains how.

Coffee and the risk of developing type 2 diabetes

Many large studies have asked whether people who drink coffee are less likely to develop type 2 diabetes. They are mostly about people who do not have diabetes yet.

  • Ding and colleagues (2014) pooled 28 studies with more than a million people. The more coffee people drank, the lower their risk of type 2 diabetes. The link was seen for both regular and decaffeinated coffee.
  • Carlström and Larsson (2018) pooled 30 studies, again with more than a million people, and found the same pattern. In their analysis, each extra daily cup was linked with a lower risk, for caffeinated and decaf alike.

These are observational studies. They show a link, not that coffee prevents diabetes. Coffee drinkers may differ from non-drinkers in other ways. The fact that decaf showed the link too suggests caffeine is not the whole story, but it does not tell us what is.

And none of this is about a sweet coffee drink. The studies counted cups of coffee; they cannot tell us what people put in them.

Coffee in people who already have diabetes

This is a different question, and the evidence is different.

Long-term studies. Shahinfar and colleagues (2021) pooled ten cohort studies of people with type 2 diabetes. Coffee drinkers had lower rates of death from any cause and from heart disease. Ding and colleagues (2025) reached a similar result for people with diabetes. Both groups were cautious. The 2021 authors rated the certainty of most findings as low or very low, and called for more research "considering type of coffee, sugar and cream added to coffee". The 2025 authors wrote that the findings "should be interpreted cautiously".

Short-term tests of caffeine. Lane and colleagues (2007) gave 20 coffee drinkers with type 2 diabetes decaf coffee, with or without added caffeine, before a test meal. With caffeine, their blood glucose rose more after the meal: the area under the glucose curve was 28% larger. This was a small, single-meal test, and the caffeine dose was fixed by the researchers. Whether the effect matters over months of ordinary coffee drinking is not something this study can show.

So the picture is mixed. Long-term studies link coffee with better outcomes, while a short test showed caffeine raising glucose after a meal. Both can be true at once, and the question is not settled. If you check your glucose, your own readings after your usual cup can tell you more about you than any study.

Other things people weigh up

  • Sleep. The ADA's Standards of Care, in the section on sleep, mention "limiting caffeine and nicotine in the evening" as one part of good sleep habits.
  • Decaf. In the risk studies above, decaf showed a link similar to regular coffee.
  • Coffee shop sizes. A large drink can be several times a small one. Many coffee pages here let you pick small, medium or large, and every food page takes an amount in ounces or grams.

If you take insulin or a medicine that can cause low blood glucose, changing a sweet coffee habit, for example switching to black coffee, changes the carbohydrate you take in. That can change how much medicine you need. Talk to your diabetes team before making a big change.

The Today page adds up what you log, so you can see what your morning coffee adds to the day. For how grams turn into carb choices, see What is a carb choice?. Sweet drinks have their own article: sugary drinks and diabetes.

Your numbers are yours

How your coffee fits depends on what is in your cup, your medicines and your glucose goals. Your doctor, diabetes educator or dietitian sets those numbers, and their advice comes before anything you read here. If you are not sure whether your usual drink is affecting your readings, take the question, and the drink's label, to your next appointment.

Sources

  • Ding M, Bhupathiraju SN, Chen M, et al. Caffeinated and decaffeinated coffee consumption and risk of type 2 diabetes: a systematic review and a dose-response meta-analysis. Diabetes Care, 2014; 37(2): 569–586. pubmed.ncbi.nlm.nih.gov/24459154 (checked 8 October 2026)
  • Carlström M, Larsson SC. Coffee consumption and reduced risk of developing type 2 diabetes: a systematic review with meta-analysis. Nutrition Reviews, 2018; 76(6): 395–417. pubmed.ncbi.nlm.nih.gov/29590460 (checked 8 October 2026)
  • Shahinfar H, Jayedi A, Khan TA, et al. Coffee consumption and cardiovascular diseases and mortality in patients with type 2 diabetes: A systematic review and dose-response meta-analysis of cohort studies. Nutrition, Metabolism and Cardiovascular Diseases, 2021; 31(9): 2526–2538. pubmed.ncbi.nlm.nih.gov/34112583 (checked 8 October 2026)
  • Ding L, Wang HP, Zhao JY, et al. Coffee and tea consumption and cardiovascular disease and all-cause and cause-specific mortality in individuals with diabetes mellitus: a meta-analysis of prospective observational studies. Frontiers in Nutrition, 2025; 12: 1570644. pubmed.ncbi.nlm.nih.gov/40525136 (checked 8 October 2026)
  • Lane JD, Hwang AL, Feinglos MN, et al. Exaggeration of postprandial hyperglycemia in patients with type 2 diabetes by administration of caffeine in coffee. Endocrine Practice, 2007; 13(3): 239–243. pubmed.ncbi.nlm.nih.gov/17599854 (checked 8 October 2026)
  • American Diabetes Association Professional Practice Committee. 5. Facilitating Positive Health Behaviors and Well-being to Improve Health Outcomes: Standards of Care in Diabetes—2026. Diabetes Care, 2026; 49(Suppl 1): S89–S131 ("Sleep Health"). pmc.ncbi.nlm.nih.gov/articles/PMC12690188 (checked 8 October 2026)
  • NIDDK. Healthy Living with Diabetes (last reviewed October 2023). niddk.nih.gov (checked 8 October 2026)
  • USDA FoodData Central: Coffee, brewed (FNDDS 2710375); Coffee, Latte (FNDDS 2710386); Coffee, Latte, flavored (FNDDS 2710389); Beverages, coffee, ready to drink, milk based, sweetened (SR Legacy 171880). fdc.nal.usda.gov (checked 8 October 2026)
  • Food figures on this page: USDA FoodData Central, via the DiabeticIndex food database.

This article is general information, not medical advice. Talk to your diabetes care team before changing how you eat or how you take your medicines.