People sitting around table drinking coffee in cafe

Caffeine and Blood Sugar: What You Should Know for Type 2 Diabetes

Wondering if you can enjoy your cup of coffee if you have diabetes? Read on to find out how caffeine impacts blood sugar with type 2 diabetes.

People sitting around table drinking coffee in cafe

Whether you’re a morning coffee or afternoon tea drinker (or both!), you’ve probably heard something about the health impacts of caffeine… This can be especially confusing since the media runs with stories talking about both positive and negative health impacts of caffeine consumption. Have you heard about the connection between caffeine and blood sugar? 

Caffeine’s impact on blood sugar can be a really confusing topic if you’re trying to do your own research. That’s why I’m here to help! By the end of this blog, you should better understand the connection between caffeine and blood sugar levels, and whether you can safely consume caffeine when you have type 2 diabetes.

Will caffeine raise blood sugar?

Testing blood with blood sugar meter

One way that caffeine can potentially increase blood sugar is through increasing cortisol levels in the body. Cortisol, a stress hormone that is central to our fight-or-flight response, increases blood sugar to provide the body with energy to either fight or flee stressful situations. Since caffeine increases cortisol, it makes sense that this can lead to blood sugar increases. 

An important thing to note is that chronic caffeine consumption leads to smaller cortisol responses over time. If you have been habitually consuming caffeine for a long time, it is very possible that your cortisol response (and thus, your blood sugar response) may not be as high as someone who has just started to consume caffeine. This is just one reason why this topic can be so complicated. Everyone is different! 

In people who do not have diabetes, it seems that up to 400 mg of caffeine consumption per day is generally safe and does not significantly impact blood glucose levels. But things can be a little different for people who have diabetes…

Caffeine’s impact on blood sugar with type 2 diabetes 

Top 6 Tips for Caffeine Consumption with Diabetes

Many studies have shown that in people with diabetes, caffeine consumption can increase blood glucose levels and further impair insulin sensitivity, leading to increased insulin resistance.  

It seems that there is also a genetic predisposition that can either increase or decrease the impact of caffeine on blood sugar. Some people naturally metabolize caffeine quicker than others. Those who metabolize caffeine slower have been shown to experience higher blood glucose levels after caffeine consumption. 

Another issue is that, for some people, caffeine consumption can negatively impact sleep duration and quality. If you have diabetes – be aware of this, because poor sleep quality can also lead to increased insulin resistance. So if you have diabetes and drink caffeinated beverages, be sure to limit your consumption by late afternoon in order to avoid this issue.

Recommended amounts of caffeine for type 2 diabetes

3 cups of coffee beans, grounded coffee and coffee drink

Like most things when it comes to diabetes, the amount of caffeine you can consume safely completely depends on your individual glycemic response. 

Some people with diabetes may need to completely avoid caffeine, while others can safely consume up to 200 mg daily without any adverse impact to their blood glucose levels. In general, 200-500 mg of caffeine per day is shown to increase blood sugar levels and decrease insulin sensitivity in people with diabetes, so it is probably best to avoid higher intakes. 

Monitoring your blood sugar can help you determine exactly how caffeine impacts you when you have type 2 diabetes. Everyone is different, so knowing how your body reacts is of key importance. 

If you’re not sure how to proceed when it comes to caffeine, be sure to speak with your diabetes care team, including your doctor and dietitian, who can help you determine your personal allowable dosage.

Common sources of caffeine

Rainbow color cups on wooden table over beautiful sky and meadow.

There are many sources of caffeine, some of which may even surprise you! Let’s dive into some common sources of caffeine to compare the potential caffeine content.


I’m sure that the very first thing you think about when it comes to caffeine sources is coffee! There are coffee shops dotting every corner in most neighborhoods, and many people start their day with a cup of joe. 

Depending on how you prepare your coffee, there are varying levels of caffeine present:

  • Freshly brewed black coffee (8 oz) = 95 mg 
  • Espresso (1 oz) = 64 mg
  • Instant (8 oz) = 62 mg
  • Cold brew (12 oz) = 155 mg 
  • Latte (8 oz) = 60-120 mg

Something that may seem a bit counterintuitive after reading how caffeine can impact blood sugar is that drinking black coffee is actually shown to decrease the risk of developing type 2 diabetes. The lower risk is seen with both caffeinated and decaffeinated coffee, so keep in mind that coffee is much more than just caffeine. 

There are some health benefits to drinking coffee beside the caffeine-kick. Coffee is a rich source of antioxidants, which may help prevent the development of certain chronic conditions, like heart disease and cancer. Micronutrients including B vitamins, manganese, magnesium, chromium, and potassium are also found in coffee. These nutrients are probably responsible for offsetting the impact of caffeine on blood sugar. 

If you have type 2 diabetes, as mentioned above, just make sure you are in tune with your blood sugar response to caffeine before consuming coffee. If you’re a coffee lover and have type 2 diabetes, there are always decaffeinated options. This way you can still obtain the beneficial micronutrients and antioxidants without the risk of blood sugar spikes. Decaf coffee typically has around 2 mg of caffeine per 8 oz. 

If you purchase coffee versus brew it yourself, be aware of flavored coffees and coffee ‘drinks.’ Many of these specialty coffee drinks contain excessive amounts of sugar and saturated fat, which counteracts  potential health benefits you could be receiving. If you do choose to drink coffee, avoid the sugary and fatty additions in order to reap the benefits without the excess calories. Luckily, most major coffee chains have their Nutrition Facts panels posted on their websites for your reference.


There are many different kinds of tea and some have more caffeine than others. The dose of caffeine also depends on the strength of the brew. Stronger teas typically have more caffeine than weaker teas.

Here is a short list of different types of teas and their caffeine content (per 8 oz):

  • Black tea = 40-70 mg
  • Green tea = 35-45 mg
  • White tea = 15-30 mg
  • Oolong tea = 37-55 mg
  • Yerba mate = 40 mg
  • Matcha = 60-70 mg

Just like coffee, tea is much more than just its caffeine content. Teas also contain many healthful nutrients and antioxidants. If you need to avoid caffeine, then opt for herbal teas such as chamomile, ginger, or peppermint. Herbal teas are naturally caffeine-free and are generally safe for people with diabetes to consume, however do keep in mind herbs can interact with medications and supplements. So always check with your physician or pharmacist if there is any potential interaction between the medication or supplement you take and an herbal tea you plan to drink.


This one may come as a shocker, but chocolate contains caffeine! Chocolate is made from cocoa beans, which contain caffeine. In general, the darker the chocolate, the higher the caffeine content. 

Dark chocolate contains the most caffeine, ranging from 20 to 120 mg per 30 grams. Milk chocolate can contain anywhere from 1 to 15 mg of caffeine. A standard candy chocolate bar usually has less than 10 mg of caffeine but is typically much higher in fat and sugars, which also impacts blood sugar levels.

Caffeinated sodas

Not all sodas contain caffeine, but many do. You should be able to determine whether or not a soft drink contains caffeine based on the label on the can or bottle. In general, the caffeine content of sodas can range anywhere from 0 to 90 mg per 12 oz serving.

Another downside of drinking soda is that many contain large amounts of added sugars. Regardless of if you have diabetes or not, consuming sugary beverages offers no health benefit and can only have a negative impact on health, so it is best to avoid these as much as possible. Plus, if you have diabetes and drink a sugary soda, this issue compounds itself when there is also caffeine present because it may further elevate blood sugar. 

Energy drinks

The entire point of energy drinks is to give you energy, so it makes sense that some brands can have massive amounts of caffeine. In general, the levels in energy drinks can range anywhere from 75 to 300+ mg of caffeine.

Most of the time, energy drinks don’t offer any beneficial nutrients to counteract the negative impacts of this level of caffeine. Some energy drinks are also packed with sugar. If you have diabetes, avoiding these high-sugar and high-caffeine energy drinks is the best course of action to prevent blood sugar spikes. 

Other sources of caffeine

Some other sources of caffeine can include sports gels, energy gums, snack bars, supplements, and medications. If food has either coffee or chocolate in it or has the word “energy” in its name, then it is very likely that it will have a decent amount of caffeine.

If you need to monitor your caffeine intake, be sure to check all labels for caffeine before consuming. If the caffeine dose is unclear, then a quick Google search may help you find your answer. And you can always reach out to the company directly to determine the caffeine level in a food or beverage if you are unsure.

The bottom line: caffeine and blood sugar for diabetes

Whether or not you choose to consume caffeine is up to you and your diabetes care team. If you have diabetes, just be aware of the various sources of caffeine and their respective dosages. In addition, some sources of caffeine are more healthful than others, so instead of grabbing a large bottle of sugary soda or a sugar-laden speciality coffee drink, try opting for an unsweetened tea or black/decaf coffee instead. 

And remember, monitoring your own personal glycemic response to caffeine is important if you have type 2 diabetes. Everyone reacts differently to caffeine, and the only way to know how you respond is to see how your blood sugar reacts. In the end, knowing how your body responds to caffeine is the key to maintaining blood sugar balance!