The short answer is that your body is doing what it is designed to do. But the mechanics behind that can be hard to understand.
The first-ever official guidelines for safe exercise were published in The Lancet journal in 2017. And more recently, in 2020, experts released an international position statement on glucose management for exercise using continuous glucose monitoring (CGM) in type 1 diabetes.
These guidelines note in particular that “weight lifting, sprinting, and intense aerobic exercise can promote an increase in BG that can last for hours,” but there’s little explanation of why this happens. And overall, the information can be overwhelming and hard to follow.
So, DiabetesMine turned to several experts in diabetes and exercise to help explain what’s going on here.
“It’s critical for your brain and your nervous system to have access to blood glucose at all times. For that reason, the body has redundant hormones that raise BG, like glucagon and adrenaline,” explained Sheri R. Colberg, PhD, professor emerita of exercise science at Old Dominion University in Norfolk, Virginia, and creator of Diabetesmotion.com. “What happens with exercise is that glucose-raising hormones are released to help pump up the amount of BG being released to match what your active muscles are using.”
Colberg admits, “The system isn’t perfect, though, and doing intense activity causes an exaggerated release of these hormones. So, when someone does intense but short activities, BG often rises due to releasing too many hormones.”
Ginger Vieira, advocate, author of several instructional diabetes books, and current digital content manager at Beyond Type 1, called on her experience as a former health coach and competitive powerlifter and Ashtanga yoga instructor to describe the effect of some of the most common mechanisms for glucose spikes during intense exercise: lactic acid, adrenaline, and fasted exercise.
Lactic acid. The process of gluconeogenesis converts lactic acid into glucose and cycles that glucose back to your muscles for fuel,” said Vieira. “This is how the body provides your muscles with fuel when you’re working too hard to cycle oxygen and glucose to your cells as your body would during general aerobic [cardio] exercise.”
Adrenaline. As commonly happens when participating in competitive sports, “your body releases adrenaline for that ‘fight or flight’ burst of energy,” described Vieira. “Adrenaline tells your liver to release stored glucose in the form of glycogen to provide the extra fuel it needs for the ‘fight’… or the soccer game. This can easily spike your blood sugar over 100 points.”
Fasted exercise. Exercising on an empty stomach can lead to a glucose spike, especially right after waking up. That’s because exercise can further exaggerate what’s known as the dawn phenomenon, when in the early morning hours, “your liver is releasing stored glucose along with morning hormones, to give your brain the fuel it needs to function,” explained Vieira.
Clearly, many mechanisms can cause a spike in glucose levels during exercise. No wonder, it can be so difficult to know what to do to bring glucose levels back down.
This content was originally published here.