Glycaemic Management Before a School Athletics Carnival
Daniel is 15 and has type 1 diabetes managed with a basal-bolus insulin regimen. He uses a continuous glucose monitor and has an HbA1c of 7.4%. He has a school athletics carnival next week and is competing in the 800 m at 10:00 am and the long jump at 1:30 pm. On a typical school day he eats breakfast at 7:00 am (two Weet-Bix, milk, banana), a sandwich at 12:30 pm, and dinner at 6:30 pm. He is anxious about hypoglycaemia during the 800 m because he had a hypo after training two weeks ago. He asks you what he should eat on the day and whether he should skip breakfast to avoid a high reading before the race. His diabetes team has given general guidance but no specific plan for competition days.
1. Explain why skipping breakfast would be an unsafe strategy for Daniel, and describe the physiological factors that make competition-day glucose management different from a usual school day.
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Skipping breakfast is unsafe for several reasons. Daniel takes a basal-bolus regimen, so his background insulin is still active in the morning regardless of whether he eats. Without carbohydrate intake, he risks hypoglycaemia before the race, particularly because exercise independently increases insulin sensitivity and muscle glucose uptake. He would also arrive at the start line with depleted liver glycogen, which is the main defence against falling blood glucose during a short, intense event. The anxiety he reports about a previous hypo is itself a reason to avoid an unpredictable strategy: a plan he understands and has practised is safer than an untested fast.
Competition days differ from school days in several ways:
- Exercise increases insulin sensitivity for hours after activity, not just during it. A race at 10:00 am can affect glucose later in the day, including around the 1:30 pm long jump.
- Intensity matters. An 800 m is high-intensity and can transiently raise glucose through adrenaline and cortisol, then cause a delayed fall. This is different from steady-state aerobic activity.
- Timing and type of carbohydrate interact with the insulin on board. Rapidly absorbed carbohydrate before exercise raises glucose quickly but may not sustain it; slower carbohydrate provides a steadier supply.
- Monitoring frequency needs to increase. A CGM gives trend data, but he should check before, during warm-up and after each event, and carry fast-acting carbohydrate at all times.
- The plan must be individualised with his diabetes team, because insulin dose adjustment is a medical decision and outside a nutritionist's scope.
2. Outline a practical eating and monitoring plan for Daniel's competition day, justifying each element with reference to digestion, absorption and glucose regulation.
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The plan should be built around predictable timing, familiar foods and frequent monitoring.
Breakfast (about 7:00 am, three hours before the 800 m). Keep a familiar breakfast with a moderate carbohydrate portion, such as Weet-Bix with milk and banana. This provides slowly digested carbohydrate that releases glucose steadily and avoids a large rapid spike. Three hours allows gastric emptying and absorption to be largely complete before the race, reducing the chance of gastrointestinal discomfort.
Pre-race check (about 9:00–9:30 am). Check the CGM and confirm with a finger-prick if the trend is falling or the reading is borderline. If glucose is low or trending down, take 15–20 g of fast-acting carbohydrate (for example, glucose tablets or juice) and recheck in 15 minutes. Fast-acting carbohydrate is appropriate here because it is absorbed quickly and corrects a falling trend before exercise begins.
During the 800 m. The event is short, so no carbohydrate is needed during the race, but fast-acting carbohydrate should be in his bag and with a supervising adult. High-intensity effort may raise glucose acutely, so he should not over-treat a high reading immediately after the race without checking the trend.
Between events (10:30 am to 12:30 pm). A small snack of carbohydrate with some protein, such as a sandwich or fruit with yoghurt, maintains glucose without a large spike. Recheck before the long jump at 1:30 pm, because post-exercise insulin sensitivity can lower glucose in this window.
After competition. Continue monitoring into the evening, as delayed hypoglycaemia is common after exercise. A meal with carbohydrate and protein supports glycogen repletion.
Safety. He should carry fast-acting carbohydrate, wear identification, and have a hypo treatment plan known to coaches. All insulin adjustments must be agreed with his diabetes team; the nutrition plan supports but does not replace that medical guidance.