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Can Intermittent Fasting Lower Blood Sugar?

Intermittent fasting is a powerful method to get high blood sugar under control. Read on to learn why it is so effective.
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Intermittent fasting is a powerful method to get high blood sugar under control. It lowers blood sugar even when intermittent fasting does not lead to weight loss. As a consequence, intermittent fasting also lowers insulin levels and improves insulin resistance.

Diabetes patients can lower their insulin dose, and research suggests that intermittent fasting helps prevent diabetes type 2.

Written by
Christine Richardson, PhD
Clinical Project Manager at Becton Dickinson

Many people try intermittent fasting because they hear it’s a great strategy to lose some weight and because there are many health benefits associated with intermittent fasting.

But are you concerned what going so long without eating may do to your blood sugar levels?

That’s a great question and hopefully this article will explain what intermittent fasting can do to your blood sugar levels so you can make an informed decision about trying intermittent fasting!

Blood Sugar Explained

Blood vessel from inside.

There is always sugar in your blood and the amount of sugar can change based on the last time you eat and what was in that meal.

However, some people have chronically elevated blood sugar levels, or blood glucose levels, and that’s a problem. This is called hyperglycemia.

When your blood sugar levels are high, your pancreas releases a hormone called insulin. Insulin helps bring sugar into your cells to use for energy and any extra sugar will go to the liver to be stored or converted into adipose tissue (body fat) (1).

If your sugar levels remain elevated, so do your insulin levels. If this continues to happen, over time, your cells won’t respond to insulin the way they should (2, 3). To put this into perspective, think about when you change your clothes. When you first put on your shirt or pants, you feel it. But within a few minutes, you no longer notice it. This same thing can happen to your body with insulin…make sense? This is called insulin resistance. 

Once your body no longer normally reacts to insulin, glucose doesn't enter the cells as easily and will build up in the blood, causing hyperglycemia 

Most people know that hyperglycemia can eventually lead to type 2 diabetes. But did you know that high sugar levels can also increase one’s risk for other conditions like atherosclerosis, cancer, inflammation, and liver damage (4, 5, 6, 7, 8)?

Keeping your blood sugar levels under control is important to maintaining a healthy life and minimizing your risk for various diseases.

Intermittent Fasting and Blood Sugar

A pile of sugar cubes.

Studies have shown that intermittent fasting can help decrease your risk of type 2 diabetes because it helps your body regulate your blood sugar. 

For example, a recent meta-analysis on twelve different studies showed that various forms of intermittent fasting helped decrease fasting blood glucose levels while helping to increase insulin sensitivity (9). 

A 2018 case report was done in three people with type 2 diabetes and reported that after a month, all three people no longer required the use of insulin injections (10).

Another study compared the effects of modified alternate day fasting (eating about 25% energy needs on fasting days) and caloric restriction in patients with type 2 diabetes. The authors reported a greater decrease in insulin and insulin resistance in the fasting group. What makes this study really interesting is that the authors also reported a similar decrease in body weight in both groups, meaning it wasn’t just the weight loss that helped improve these patients’ insulin resistance, it was intermittent fasting (11). 

Additionally, other studies have shown that some individuals who try intermittent fasting can decrease their blood sugar levels without losing weight. This is particularly interesting because these studies show that the decrease in blood sugar levels isn’t a result of the weight loss achieved through intermittent fasting but is instead a direct result of intermittent fasting alone (12, 13).

However, other studies have shown that intermittent fasting alone doesn’t help decrease blood sugar levels (14, 15). Don’t let this confuse you though! The participants who saw a significant decrease in their blood glucose levels had hyperglycemia and/or type 2 diabetes when they started the study. 

This means that if you have high blood glucose levels, intermittent fasting can help you get control of your blood sugar levels. And if you don’t have hyperglycemia, this is actually good news because you don’t want your blood sugar levels to get too low. This means that intermittent fasting shouldn’t cause an unhealthy drop in your blood sugar levels…yay!

However, if you are prone to low blood sugar levels or are concerned about this for any reason, we encourage you to meet with your primary care physician before starting an intermittent fasting routine. You can also buy blood glucose monitors so that you can keep an eye on your sugar levels while at home.

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How Does it Work?

Now that we’ve talked about how intermittent fasting influences blood sugar levels, you may be wondering how this happens. Well, there are a number of ways intermittent fasting helps maintain blood sugar levels:

  1. Fasting can help increase how efficiently your cells take in glucose

There are certain compounds other than insulin that help glucose get into cells; they’re called GLUT receptors. Fasting increases their production, which means that glucose gets into your cells faster, meaning your blood glucose levels decrease (16, 17, 18).

  1. Loss in body fat

Studies have shown that excess body fat also means extra fat in your liver. For insulin to work properly, there are body pathways that allow it to work. Having extra body fat can cause an increase of fat in your blood, which can prevent these pathways from working normally. This can cause insulin resistance while also causing your liver to release more glucose into your blood (19, 20).

  1. Decrease in inflammation 

Different inflammatory compounds can cause the body to not respond as well to insulin, which directly contributes to insulin resistance (7, 21, 22). 


Having high blood glucose levels puts you at risk for developing type 2 diabetes.

If you have hyperglycemia and don’t have type 2 diabetes yet, intermittent fasting may be a good strategy to use to get your blood sugar levels under control.

If you don’t have hyperglycemia, intermittent fasting shouldn’t cause your blood sugar levels to get too low. 


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2. Taylor R. Insulin resistance and type 2 diabetes. Diabetes. American Diabetes Association; 2012. p. 778–9. 

3. Wilcox G. Insulin and Insulin Resistance. Clin Biochem Rev [Internet]. The Australian Association of Clinical Biochemists; 2005 [cited 2020 Jul 29];26:19–39. Available from:

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9. Cho Y, Hong N, Kim K, Cho S, Lee M, Lee Y, Lee Y, Kang E, Cha B-S, Lee B-W. The Effectiveness of Intermittent Fasting to Reduce Body Mass Index and Glucose Metabolism: A Systematic Review and Meta-Analysis. J Clin Med [Internet]. MDPI AG; 2019 [cited 2021 May 18];8:1645. Available from: /pmc/articles/PMC6832593/

10. Furmli S, Elmasry R, Ramos M, Fung J. Therapeutic use of intermittent fasting for people with type 2 diabetes as an alternative to insulin. BMJ Case Rep [Internet]. BMJ Publishing Group; 2018 [cited 2021 May 18];2018. Available from: /pmc/articles/PMC6194375/

11. Gabel K, Kroeger CM, Trepanowski JF, Hoddy KK, Cienfuegos S, Kalam F, Varady KA. Differential Effects of Alternate-Day Fasting Versus Daily Calorie Restriction on Insulin Resistance. Obesity [Internet]. Blackwell Publishing Inc.; 2019 [cited 2021 May 21];27:1443–50. Available from: /pmc/articles/PMC7138754/

12. Sutton EF, Beyl R, Early KS, Cefalu WT, Ravussin E, Peterson CM. Early Time-Restricted Feeding Improves Insulin Sensitivity, Blood Pressure, and Oxidative Stress Even without Weight Loss in Men with Prediabetes. Cell Metab. Cell Press; 2018;27:1212-1221.e3. 

13. Jamshed H, Beyl RA, Manna DLD, Yang ES, Ravussin E, Peterson CM. Early time-restricted feeding improves 24-hour glucose levels and affects markers of the circadian clock, aging, and autophagy in humans. Nutrients. MDPI AG; 2019;11. 

14. Soeters MR, Lammers NM, Dubbelhuis PF, Ackermans MT, Jonkers-Schuitema CF, Fliers E, Sauerwein HP, Aerts JM, Serlie MJ. Intermittent fasting does not affect whole-body glucose, lipid, or protein metabolism. Am J Clin Nutr [Internet]. Oxford Academic; 2009 [cited 2021 May 18];90:1244–51. Available from:

15. Carlson O, Martin B, Stote KS, Golden E, Maudsley S, Najjar SS, Ferrucci L, Ingram DK, Longo DL, Rumpler W V., et al. Impact of reduced meal frequency without caloric restriction on glucose regulation in healthy, normal-weight middle-aged men and women. Metabolism [Internet]. NIH Public Access; 2007 [cited 2021 May 18];56:1729–34. Available from: /pmc/articles/PMC2121099/

16. Habegger KM, Hoffman NJ, Ridenour CM, Brozinick JT, Elmendorf JS. AMPK enhances insulin-stimulated GLUT4 regulation via lowering membrane cholesterol. Endocrinology. The Endocrine Society; 2012;153:2130–41. 

17. Viollet B, Horman S, Leclerc J, Lantier L, Foretz M, Billaud M, Giri S, Andreelli F. AMPK inhibition in health and disease. Critical Reviews in Biochemistry and Molecular Biology. Inserm; 2010. p. 276–95. 

18. Grahame HD. AMPK: A target for drugs and natural products with effects on both diabetes and cancer. Diabetes. Diabetes; 2013. p. 2164–72. 

19. Hajer GR, Van Haeften TW, Visseren FLJ. Adipose tissue dysfunction in obesity, diabetes, and vascular diseases. [cited 2020 Jul 2]; Available from:

20. Sears B, Perry M. The role of fatty acids in insulin resistance [Internet]. Lipids in Health and Disease. BioMed Central Ltd.; 2015 [cited 2021 May 18]. Available from: /pmc/articles/PMC4587882/

21. Sokolowska E, Blachnio-Zabielska A. The Role of Ceramides in Insulin Resistance. Frontiers in Endocrinology. Frontiers Media S.A.; 2019. 

22. Summers SA. Ceramides in insulin resistance and lipotoxicity. Progress in Lipid Research. 2006. p. 42–72. 

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