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Diabetes Knowledge

Do Protein and Fat Impact Your Glucose Levels?

6/20/2021 by Hope Warshaw

Do Protein and Fat Impact Your Glucose Levels?

To understand the impact of protein and fat on glucose levels let’s take one step back to gain an understanding of the relationship between the three macronutrients we eat - carbohydrate, protein and fat.

The Macronutrients 

The calories we eat provides our body with energy. Calories come mainly from the three macronutrients (macro meaning big) - carbohydrate protein and fat. (Note: alcohol, if you drink it, does provide calories). 

We don’t eat carbohydrate, protein and/or fat separately. We eat foods and drink beverages that contain more or less of these nutrients. Think of the foods and beverages you eat and drink as packages of carbohydrate, protein and fat.1 

Here are a few examples: 

  • Low-fat (2%) milk contains mainly carbohydrate, protein and a small amount of fat. 
  • A grilled chicken thigh (with no sauces or seasonings added) contains no carbohydrate, mostly protein and a small amount of fat. 
  • Corn on the cob (with nothing on it) contains mainly carbohydrate and a small amount of protein.
  • Peanut butter contains mainly fat and some protein. 

Get the picture of foods as packages of nutrients?    

The Macronutrient Balance

If you aim to eat a similar number of calories day to day and you, for example, choose to eat less carbohydrate, you will, just based on the macronutrients in foods, eat more protein and fat to meet your calorie needs. 

On the converse if you’re an ovo-lacto vegetarian (meaning you eat dairy foods and eggs), the majority of your calories will likely be carbohydrate and you’ll eat less protein and fat. 

Suffice to say, there is no one right way to eat healthfully with diabetes.2 What is most important is that you find an eating pattern - a combination of foods or good groups - that fits your desired way of eating that promotes staying healthy.  

In 2019, the American Diabetes Association published their latest nutrition guidance.2 This guidance underscores four key recommendations you can consider to be, “eating pattern common denominators”: 

  • Emphasize eating non-starchy vegetables  
  • Minimize foods and beverages that contain added sugars and refined grains
  • Choose whole foods over highly processed foods 
  • Replace sugar-sweetened beverages with water as often as possible

Notice that these key recommendations focus squarely on actions to take when you select carbohydrate-containing foods. A second focus is on quality. The NHS also encourages you to choose foods that contain carbohydrate with one or more of the following: whole grains, dietary fibers, and vitamins and minerals.³ 

When it comes to the amount of carbohydrate to eat, ADA’s guidance concludes that reducing (not severely restricting or eliminating) the total amount of carbohydrate you eat can help you improve your glucose levels over time.2 

Do not severely restrict healthy sources of carbohydrate and eat loads of protein and fat as a way to manage your glucose levels. If you can’t, through healthy eating, hit the glucose and A1C targets that you and your clinicians set then you may need to take glucose lowering medication.⁴ 

This doesn’t mean you’re bad or a failure (you can blame your pancreas!). It simply means that your type 2 diabetes has progressed. Checking your glucose levels regularly (see section below) will paint the picture of the ups and downs of your glucose levels. 

On to Protein and Fat

As we discuss protein and fat, go back to the analogy that foods are packages of nutrients. While some foods contain mainly protein, like chicken breast, white fin fish, tuna fish (not tuna fish salad) and shrimp; many foods with protein are relatively high in fat. Consider: many cuts of red meats, cheese, eggs and nuts. As for fat, some foods contain mainly fat.⁵ 

For example: oils, butter, salad dressings, mayonnaise, and cream cheese. One more note about foods or meals that contain protein and fat…they can help you feel fuller longer in contrast to foods and meals that are higher in carbohydrate and lower in protein and fat.⁵   

  • Protein and Type 2 Diabetes: Research shows that a moderate amount of protein, which is what most Americans eat, increases the amount of insulin your pancreas produces (if your pancreas still makes ample insulin), but this amount of protein doesn’t increase glucose levels.⁶ ⁷ 
  • Protein and Type 1 Diabetes: Research shows that low to moderate amounts of protein will not greatly increase glucose levels after eating.⁸ However, high protein meals, which may well be high fat meals (think prime rib, baked potato stuffed with butter and sour cream), can raise glucose levels more after eating. 

This rise may happen slowly at first, and then glucose can rise higher several hours after eating. To manage after meal glucose levels when eating higher protein and fat meals that contain some carbohydrate, ADA recommends that a person’s insulin dose should not solely be based on the carbohydrate count of the meal or snack.

In fact, people may need to take more meal-time insulin, adjust the timing of the dose or split the dose.² ⁶ ⁷  Checking glucose levels three hours after eating these meals can offer insights to individualize an approach that works well for you.2 

  • Fat and Diabetes: Fat seems to impact glucose levels in people with type 1 and 2 similarly.⁶ ⁷  A high-fat meal can more slowly raise glucose levels than a high-carbohydrate meal. 

This seems to be because fat slows the rate at which the food eaten is digested, but once digested, the carbohydrate part of the meal does raise glucose. Fat also seems to decrease the body’s sensitivity to insulin, which slows the rise of glucose.⁶ ⁷  And lastly, research shows that choosing foods rich in polyunsaturated and monounsaturated fats (like nuts and seeds) can help improve blood glucose management in people with type 2 diabetes. So choose these more often than foods high in saturated fats (like cheese and red meat.)⁶ ⁷

You are You, Your Diabetes is Your Diabetes

Research continues to show varying glucose responses to varying combinations and amounts of carbohydrate, protein and fat in meals and snacks. This makes giving one set of recommendations on this topic a challenge. There’s simply no one recipe for success! Get to know yourself and your glucose responses by checking, tracking and learning (see Check, Track and Learn). 

Check, Track and Learn 

The best advice is to check your glucose regularly, track all your results, then sit back and learn. Rotate when you check your glucose…sometimes when you wake up, before different meals, sometimes an hour, two or three after you start to eat. Check after a low or high carbohydrate meal, or after you eat a high protein and fat meal. The list goes on. Results are not good or bad. They are simply information for learning. Make time to review your results yourself. Make observations and record them.  Then share them with your clinicians. Together come up with your next steps to manage your glucose levels.

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  1. Evert A.B., Factors beyond carbohydrate to consider when determining meantime insulin doses: protein, fat, timing, and technology. Diabetes Spectrum. [online] Available at:
  2. Evert, A.B., Dennison, M., Gardner, C.D., Garvey, W.T., Karen Lau, K.H., MacLeod, J., Mitri, J., Pereira, R.F., Rawlings, K., Robinson, S.R., Saslow, L., Uelmen, S., Urbanski, P.B., Yancy, W.S., 2019. Nutrition therapy for adults with diabetes or prediabetes: A consensus report. Diabetes Care. [online] Available at:  
  3. NHS, 2020. Starchy foods and carbohydrates. [webpage] Available at: [Accessed 22/01/2021].
  4. Mayo Clinic, 2021. Type 2 diabetes. [webpage] Available at: [Accessed 22/01/2021].
  5. Medical News Today, 2019. What to know about low-carb, high fat diets. [webpage] Available at: [Accessed 22/01/2021].
  6. Warshaw, H.W., 2016. Diabetes Meal Planning Made Easy. 5th ed. Virginia: American Diabetes Association.
  7. Franz, M.J., 2016. Diabetes Nutrition Therapy: Effectiveness, Macronutrients, Eating Patterns and Weight Management. Am J Med Sci. [online] Available at: 
  8. Franz, M.J., 2000. Protein Controversies in Diabetes. Diabetes Spectrum. [online] Available at:

The mySugr website does not provide medical or legal advice. mySugr blog articles are not scientific articles, but intended for informational purposes only.

Medical or nutritional information on the mySugr website is not intended to replace professional medical advice, diagnosis or treatment. Always consult a physician or health care provider with any questions you may have regarding a medical condition.

Hope Warshaw

Hope Warshaw, MMSc, RD, CDCES, BC-ADM, is a nationally respected Registered Dietitian and Certified Diabetes Care and Education Specialist. She has spent her career, spanning over 40 years, involved in the care and management of people with diabetes. She is the author of several books published by the American Diabetes Association, including Diabetes Meal Planning Made Easy (5th ed) and Eat Out, Eat Well – How to Eat Healthy in Any Restaurant