What causes high blood sugar?

By Dr. Priyanka Wali

Many things can cause high blood sugar, but what we eat plays the biggest and most direct role in elevating blood sugar. When we eat carbohydrates, our body converts those carbohydrates into glucose, and this can play a role in raising blood sugar. Protein, to a certain degree, in high amounts can also raise blood sugar levels. Fat does not raise blood sugar levels. Stress leading to an increase in the hormone cortisol can also raise blood sugar levels.

how carbs, protein and fat affect blood insulin

Learn more in Dr. Sarah Hallberg’s video on how what we eat impacts our blood sugar.

Back to Diabetes FAQ

Related blog posts

Is There a Role for Short-Term Ketosis in Long-Term Care for Type 2 Diabetes? - Weight loss is the standard first step prescribed for overweight people with type 2 diabetes. However, this is notoriously difficult… ... Read More
Dr. Hallberg Ted Talk Reversing Diabetes Dr. Sarah Hallberg’s Ted Talk: Reversing Type 2 Diabetes Starts with Ignoring the Guidelines - Our Medical Director, Dr. Sarah Hallberg, gave a talk for TedxPurdueU that has taught millions of people how food affects… ... Read More
Sarah Hallberg, DO, MS Reversing Diabetes 101 with Dr. Sarah Hallberg: The Truth About Carbs, Blood Sugar and Reversing Type 2 Diabetes - You may have heard a lot about type 2 diabetes, but do you know what it actually does to your… ... Read More


  1. Avatar

    Could eating a fatty meal slow down digestion and make it harder for insulin to work? I am T1 and have been following a low carb diet for sometime. I also eat healthy fats to help with satiety however note my blood sugar levels have escalated especially after dinner. Recently, my DE advised me to cut down on fats.
    Would appreciate any clarity.
    Thank you in advance.


    1. Virta Health

      Thanks for your question, Julie! While fat can slow digestion, it is typically helpful in stabilizing blood sugar levels versus driving them up. Carbs and, to some small extent, protein can increase blood sugar levels while fat does not stimulate a blood sugar response. I would encourage you to work with your healthcare provider on identifying what else may be contributing to those elevated levels after dinner.


  2. Avatar

    This chart is misleading since it shows blood insulin not blood sugar. Yet the text is all about blood sugar.

    Protein does not raise blood sugar significantly. In fact, for many people protein actually drops blood sugar. That is because of the action of glucagon which lowers blood sugar when protein is eaten. In Type 2 diabetics there may be a small rise.

    Easy enough to test with Whey Protein. Eat 50g of zero carb whey and measure blood sugar. Very modest rise in diabetics and there’s actually a drop in non-diabetics.


Leave a reply

Your email address will not be published.