Preventing Lows During Exercise

Cardio workouts are fantastic for your heart, but they are notorious for tanking blood sugar! When you do aerobic exercise (like running, cycling, or swimming), your muscles rapidly consume glucose for fuel. On top of that, physical activity makes your body much more sensitive to whatever insulin is already in your system.

To break the cycle of dropping low and having to eat back the calories you just burned, timing and strategy are key. First, try to avoid exercising during the "peak" action time of your rapid-acting insulin (usually 1-2 hours after a meal bolus). If you have a lot of active insulin on board, cardio will act like an accelerator, causing a severe drop.

If you know you will be working out after a meal, you can ask your doctor about reducing your mealtime insulin dose beforehand. If you exercise on an empty stomach, try eating a small snack with complex carbohydrates and protein—like half an apple with peanut butter—about 30 minutes before you start.

Additionally, keep in mind that different exercises affect blood sugar differently. While cardio usually drops it, anaerobic exercise like heavy weightlifting or high-intensity interval training (HIIT) can actually cause a temporary spike due to adrenaline. Balancing the two types of exercise can sometimes help keep your numbers steady!