We often get asked: What should my glucose levels be when not training?
To which the simple answer is: stay in the Blue Zone, or the Glucose Recovery Zone (GRZ). That’s because maintaining glucose stability and prevent high glucose levels is key to managing inflammation and promoting a faster recovery.
But, that’s an oversimplification. Sometimes, glucose rushes can be beneficial to refuel and replenish your body. Context is key. In this article, we’ll explore why:
- Not all Glucose Rushes are bad.
- Rushes need to be managed, not avoided.
What is a Glucose Rush?
Any upward movement of glucose levels are oftentimes called spikes. But, not all “spikes” are created equal. At Supersapiens, we distinguish between a glucose “Rush” and a glucose “Rise” to help you understand how to achieve better glucose control and the associated benefits.
At Supersapiens, we distinguish between a glucose “Rush” and a glucose “Rise” to help you understand how to achieve better glucose control.
Whereas a Glucose Rise is a more stable and controlled increase in your glucose levels, a Glucose Rush is a quick and significant increase in your glucose levels, which often results in glucose levels above 140 mg/dL and subsequent instability in your glucose levels over the next few hours.
A Rush notification is triggered in the Supersapiens app when your glucose levels sharply trend up at a rate of 10 mg/dL or more within a 5 minute period, are trending above your blue recovery zone, or have increased more than 55 mg/dL.
Why can Glucose Rushes be Bad?
Some glucose Rushes, such as immediately after exercise, can be good. But there are situations where a Glucose Rush can be bad. Here are some of the effects of poorly-timed Glucose Rushes:
- Metabolic perturbations like steep glucose changes may impact metabolic homeostasis and therefore metabolic flexibility.
- Glucose Stability (no Glucose Rushes) is associated with improved mood, higher energy levels, and reduced hunger.
- Glucose levels above 140 mg/dL trigger a significantly higher release of insulin. In certain situations such as training to target fat oxidation, high circulating insulin levels can negatively influence lipolysis and our capacity to rely on fat as a fuel. It also impacts our available circulating glucose levels, which can seriously impede high intensity training. It also depresses glucose release from the liver and therefore potentially impedes glucose control.
- Glucose Rushes can result in “rebound hypoglycemia” (aka reactive hypoglycemia, a period of really low glucose right after a Glucose Rush).
In people without diabetes, glucose is regulated fairly tightly by the body. However, what was previously thought to be extremely tight regulation is now being proved inaccurate. After a few years of tracking athletes with CGM, glucose levels in athletes without diabetes are both more variable, have a greater range, and can be sustained at much higher levels than previously thought possible.
For these athletes, increases in glucose reflect very normal physiology and can even be used to your advantage (more on this later). And extremely dysregulated glucose levels may be a sign of fatigue, overtraining, and under-fueling.
Seeing very low glucose levels (compared to your normal) and/or glucose levels which are excessively stable (less Rushes or Rises compared to your normal) may both be signs of under-fueling. Athletes like Lisa Norden who use Supersapiens to track her nutrition have also noticed on this.
How Do I Know Which Glucose Rushes Should be Avoided?
- Glucose Rushes that are excessively high, significantly exceeding 140 mg/dL.
- Glucose Rushes that keep your glucose levels high for a long time before returning to normal.
Excessive and frequent exposures to excessively high glucose levels can lead to impaired glucose tolerance, insulin resistance, and chronic hyperglycemia. This in turn can lead to general inflammation, mood and energy swings, and the development of potential long-term health consequences.
Insulin: What’s the Story There?
When glucose levels go up, insulin is the main hormone released to partition glucose from the blood into the cells either for immediate use or storage. Insulin release represents the first and main defense mechanism against high glucose levels. It is considered a “storage hormone” since all excess glucose that is not used by the working cells is stored for future use.
For more on the basics of glucose and insulin, check out our article here.
If you have too much insulin in your system, and for too long, one may start to develop insulin resistance. That means your metabolism doesn’t work as efficiently and you need more insulin to regulate the same amount of glucose. This cycle of more glucose and more insulin when not consumed in proximity to exercise can lead to a myriad of health concerns.
Additionally, insulin also suppresses liver glucose output and gluconeogenesis (production of new glucose from within your body) while blunting fat oxidation capacity.
On the flip side, insulin is a growth hormone and can have positive effects on your recovery. Insulin promotes glycogen replenishment and stimulates protein synthesis if substrates are available. So, a Glucose Rush immediately after exercise can rebuild, restore, and replenish.
Before a race or big workout, carbohydrate loading is supported by insulin by storing glucose in your muscles in the form of glycogen. Tip: don’t carb load too close to the start of an event so your body has time to clear the circulating insulin levels. More on this below.
Side note: your body’s metabolism works differently when you are active. Your body can uptake glucose without releasing insulin during exercise, which is why high glucose levels do not have the same effects during exercise. When showing your real-time glucose levels, the Supersapiens app shows a “Perform” screen and a “Recover” screen for this reason.
How to Better Manage Glucose Rushes
There are two general approaches to managing Glucose Rushes: First, knowing when a Glucose Rush is positive. Second, knowing how to turn a potential Rush into a Rise.
A Glucose Rush can be beneficial or detrimental depending on the situation or timing. Glucose Rushes need to be appropriately timed, not avoided. It should be noted that one cannot specifically influence our body’s physiology, but one CAN influence our metabolic response by changing some of our behaviors for the positive.
A Glucose Rush can be beneficial or detrimental depending on the situation or timing. Glucose Rushes need to be appropriately timed, not avoided.
For example, post-prandial walking and ordering your macronutrients can change your glucose response. For more on turning a Rush into a Rise see this article.
When Might Glucose Rushes Be Good?
Try to find meals that induce a Glucose Rush without triggering a rebound low or significant metabolic imbalance. A Glucose Rush prior to a big race tops off your glycogen stores through the support of insulin. An important consideration is timing here. If your Glucose Rush is too close to the start of an event, you may get some other negative effects if circulating insulin levels are still high at race time. So try to ensure it is at least 3 hours before your event. For more information on optimal timing of pre-race glucose intake, check this out.
Ultimately it’s a trade off: if your timing is off and insulin is too high, then insulin would impair your body’s capacity to rely on fat as a fuel. But the right amount of glucose and the right amount of insulin at the right time can be extremely beneficial and seriously upgrade your performance.
Glucose Rushes in the post-exercise window can take advantage of the actions of insulin to optimize glycogen replenishment and protein synthesis–as long as both carbs and protein are available. After exercise, your muscles are already very sensitive to glucose uptake regardless of insulin level. However, the insulin action is additive and can enhance the muscles’ glucose uptake and glycogen replenishment. So don’t be scared to try to eat something quite high in carbohydrates and protein to ensure you take advantage of the post workout window to optimize your recovery.
If you are interested in more details on optimizing glucose levels for recovery, check out this article.
- Not all Glucose Rushes are bad.
- Glucose Rushes can be bad when longer, higher, and not in proximity to exercise.
- Rushes need to be managed, not avoided.
- Glucose Rushes should be managed for your goals and current situation with optimal timing.
Empowered with this information and visibility to your own glucose levels, you should be able to make great progress towards your goals. When you’re ready to upgrade your metabolic efficiency, you can get your own glucose biosensors here.
For more information and FAQs about Glucose Rushes see this.
- Mata F, Valenzuela PL, Gimenez J, Tur C, Ferreria D, Domínguez R, Sanchez-Oliver AJ, Martínez Sanz JM. Carbohydrate Availability and Physical Performance: Physiological Overview and Practical Recommendations. Nutrients. 2019 May 16;11(5):1084. doi: 10.3390/nu11051084. PMID: 31100798; PMCID: PMC6566225
- Wyatt, P., Berry, S.E., Finlayson, G. et al. Postprandial glycaemic dips predict appetite and energy intake in healthy individuals. Nat Metab 3, 523–529 (2021). https://doi.org/10.1038/s42255-021-00383-x
- Page KA, Seo D, Belfort-DeAguiar R, Lacadie C, Dzuira J, Naik S, Amarnath S, Constable RT, Sherwin RS, Sinha R. Circulating glucose levels modulate neural control of desire for high-calorie foods in humans. J Clin Invest. 2011 Oct;121(10):4161-9. doi: 10.1172/JCI57873. Epub 2011 Sep 19. PMID: 21926468; PMCID: PMC3195474.
- Frayn K N. Metabolic Regulation: A Human Perspective. Wiley-Blackwell. 3rd Edition. March 2013 ISBN: 978-1-118-68533-4
- Aronoff, S. L., Berkowitz, K., Shreiner, B., & Want, L. (2004). Glucose Metabolism and Regulation: Beyond Insulin and Glucagon. Diabetes Spectrum, 17(3), 183–190. https://doi.org/10.2337/diaspect.17.3.183
- Brun JF, Fedou C, Mercier J. Postprandial reactive hypoglycemia. Diabetes Metab. 2000 Nov;26(5):337-51. PMID: 11119013.
- Bouskila M, Hirshman MF, Jensen J, Goodyear LJ, Sakamoto K. Insulin promotes glycogen synthesis in the absence of GSK3 phosphorylation in skeletal muscle. Am J Physiol Endocrinol Metab. 2008 Jan;294(1):E28-35. doi: 10.1152/ajpendo.00481.2007. Epub 2007 Nov 14. PMID: 18003720.
- Fujita S, Rasmussen BB, Cadenas JG, Grady JJ, Volpi E. Effect of insulin on human skeletal muscle protein synthesis is modulated by insulin-induced changes in muscle blood flow and amino acid availability. Am J Physiol Endocrinol Metab. 2006;291(4):E745-E754. doi:10.1152/ajpendo.00271.2005
- Baur DA, Saunders MJ. Carbohydrate supplementation: a critical review of recent innovations. Eur J Appl Physiol. 2021 Jan;121(1):23-66. doi: 10.1007/s00421-020-04534-y. Epub 2020 Oct 27. PMID: 33106933.
- Margolis LM, Allen JT, Hatch-McChesney A, Pasiakos SM. Coingestion of Carbohydrate and Protein on Muscle Glycogen Synthesis after Exercise: A Meta-analysis. Med Sci Sports Exerc. 2021 Feb 1;53(2):384-393. doi: 10.1249/MSS.0000000000002476. PMID: 32826640; PMCID: PMC7803445.
- Tabák, Adam G et al. “Prediabetes: a high-risk state for diabetes development.” Lancet (London, England) vol. 379,9833 (2012): 2279-90. doi:10.1016/S0140-6736(12)60283-9