Type 1 Diabetic Cyclist with Hypoglycemia During Race
A 35-year-old male with type 1 diabetes on an insulin pump is competing in a 120-mile gran fondo. His basal rate is set at 1.0 U/hr. He checks his glucose before the start: 180 mg/dL. He plans to eat a pre-race meal and bolus normally. During the race, at mile 60, he becomes confused, sweaty, and shaky. His continuous glucose monitor (CGM) reads 55 mg/dL with a downward trend. He has a gel with 20 g of carbohydrates. He is able to swallow. After treatment, his glucose rises to 90 mg/dL. He wants to continue. His teammate asks if he should reduce his basal rate or suspend his pump during exercise.
1. What is the immediate treatment for his hypoglycemia, and what adjustments should be made to his insulin regimen during exercise?
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Immediate treatment: give 15-20 g of fast-acting carbohydrates (he has a gel, which is appropriate). Recheck glucose in 15 minutes. If still <70 mg/dL, repeat. Once glucose is >70 mg/dL, he can continue but should eat a snack with complex carbs and protein. For exercise: reduce basal insulin by 50-80% during exercise, or suspend the pump for 1-2 hours before exercise if possible. Since he is on a pump, he can set a temporary basal rate. He should also reduce the pre-race bolus for the meal by 25-50% if exercise is within 2 hours. He should check glucose every 30 minutes during exercise. He should carry glucagon. He should not exercise if glucose >250 mg/dL with ketones.
2. What are the key safety considerations for his participation in endurance events?
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He should have a medical alert ID, carry a glucose meter and supplies, and inform race organizers and teammates about his condition. He should have a plan for hypoglycemia and hyperglycemia. He should monitor glucose closely and adjust insulin and carbohydrate intake based on exercise intensity and duration. He should avoid exercise if glucose is >250 mg/dL with moderate or large ketones. He should have a sick-day plan. He should also be aware of the effects of altitude and heat on glucose and insulin absorption. Regular follow-up with his diabetes care team is essential.