Glucose is impacted by many factors. The magnitude of effect that any one of these factors has is dictated by the strength of the stimulus and its temporality to the current glucose reading. That is, the stronger its influence the more likely you are to see its impact and the more recently it occurred the more likely you are to see the impact.
All of that said, the three biggest and most notable factors that impact glucose are food, mood (stress) and movement.
Mood is our label for all emotional states which may increase glucose. These often relate to adrenaline’s role in driving glucose up which is classically due to stress or anxiety but can also be due to excitement.
Mood is the label given to any number of emotional states which may drive glucose. Generally these are events that cause a release of adrenaline which in turn mobilizes glucose. Classically stress or anxiety can do this, but so can excitement of course.
The extent that glucose increases is proportional to the increase in adrenaline, given the nature of most peoples’ lives in the modern world and the myriad of factors impacting glucose, it may be that some users have not noticed the impact of mood or stress on their glucose yet.
A few situations that may yield increases we have heard from users; the dentist, in-flight turbulence, meetings, race start lines and work presentations (see below).
Whilst the inciting presentation and glucose response is immediately apparent in the above glucose trace, it is worth noting a few more subtle details. There are some pre-presentation nerves that are clearly playing a role, with glucose creeping up for the half hour preceding the presentation. Similarly, whilst the presentation was only half an hour long, the stress of the situation took time to dissipate, particularly in the context of minimal glucose utilization (in contrast to something like a race start line where glucose is used once movement starts).
In different situations and at different intensities, movement can either increase or decrease glucose.
Recently, post meal walking has been popularized as a method of managing post-prandial glucose rushes and improving glucose stability. This is a good example of the glucose lowering effects of exercise, where muscle contraction causes insulin-independent glucose uptake.
Conversely, if metabolic stress and/or exercise intensity is high enough, this can increase glucose levels. It can, however, be hard to separate the impacts of adrenaline (from excitement or psychological stress) from other drivers of glucose increase in some exercise settings (for example during competition). That said, broadly exercise that is metabolically stressful enough, will increase glucose levels, which excludes some forms of strength training such as very traditional strength protocols (low reps, long rests) and endurance training (long slow distance, or zone 2 training).
An example of exercise’s impact on glucose levels can be seen below from a Supersapiens team member’s Dashboard data:
In the above data you can see the team member’s morning commute cycle. Which is a great example of low intensity exercise and its minimal impact on increasing glucose, though it would have decreased glucose if it was elevated.
In addition to this cycling commute you can see 3 runs; all 5km long; a warm up, 5k maximal effort and then cool down.
The maximal effort is around 17 mins in duration, and the increasing glucose in response to this metabolic stress is visible during the effort. Most interestingly though, glucose continues to increase after the event, this is almost certainly a result of ongoing delivery of glucose with relatively lower utilization (because the maximal effort is over and the team member is either resting or warming down at low intensity). The increasing glucose due to mismatched delivery and utilization is explained well in this article which discusses how continuous glucose monitors (CGMs) measure glucose.
The significant drop in glucose, and its swift rate, during cool down are worth noting here. The team member had all classic hypoglycemic symptoms (dizziness, excessive sweating and needing to slow down) associated with this, something not always the case for this team member. The team member regularly feels these hypoglycemic episodes, but only when they are associated with a significant drop in glucose, not when their glucose is 65mg/dL or similar as it is in the above case. That is, the symptoms experienced seem to be more related to a rate of change in this case than the actual glucose level measured. This is similar to what Dr Howard Zisser mentioned in our discussion with him on the Supersapiens Podcast.
In these situations, there is research suggesting that carbohydrate supplementation can help address the symptoms of this hypoglycemia. That said, sometimes carbohydrate boluses can be the driver of something similar as is seen below in figure 4.
Perhaps the easiest aspect of CGM to understand is the acute impact of food, specifically higher carbohydrate foods. Generally when consuming carbohydrates, particularly simpler forms and/or more processed foods you will notice an increase in glucose. This may or may not be accompanied by a resultant drop in glucose below its starting point before re-normalizing.
Glucose Response to Coke
Some internal experimentation at Supersapiens, amongst the team, included fasting overnight followed by drinking a coke. This sort of experiment limits confounding variables, as the overnight fast, in addition to minimal activity prior to ingestion, helps to show the impact of the food/beverage alone. One team member’s response can be seen below.
As mentioned previously, the impact of movement on glucose uptake is significant and thus if mistimed, the effects of insulin and movement induced glucose uptake can be somewhat additive and result in particularly low glucose. This is something that can impact how athletes feel and their glucose as they start exercising as discussed in this article.
Perhaps unsurprisingly for readers, insulin release during exercise is relatively minimal as glucose can be used by muscles in absence of insulin (and the additive effect of the two is likely riskier to the organism than slightly higher glucose for a period of time whilst exercising). There are some times where this is not the case of course, because metabolism is more akin to a dimmer switch than an on/off switch. In the below figure you can see a scenario where a Supersapiens team member testing a new nutrition product on an easy run, suffered a rebound hypoglycemic event, complete with dizziness, excessive sweating and having to slow down.
Given the above, the nuance in glucose rushes and glucose stability should be clearer to readers.
That is, whilst glucose stability is the objective, this is because behaviors that improve glucose stability are generally healthy ones for example exercise and fiber intake. Remembering the goals are health and performance, not perfect glucose. Users should not be trying to avoid high intensity training because it causes glucose rushes, similarly whilst stress is not ideal, the body mobilizing glucose as a result of stress isn’t inherently bad.
- Ertl AC, Mann S, Richardson A, Briscoe VJ, Blair HB, Tate DB, Davis SN. Effects of oral carbohydrate on autonomic nervous system counterregulatory responses during hyperinsulinemic hypoglycemia and euglycemia. Am J Physiol Endocrinol Metab. 2008 Sep;295(3):E618-25. doi: 10.1152/ajpendo.90470.2008. Epub 2008 Jul 8. PMID: 18612042; PMCID: PMC2536735.