The three daily levers: food, insulin timing and movement

Three things move blood sugar every single day, and they are the levers a person with type 1 pulls several times a day. This page gives a short overview of each — food, insulin timing and movement — and points to the deeper sections.

• Food pushes glucose up. Carbohydrate does nearly all of it, fast. Fat and protein arrive late and quietly.
• Insulin pushes glucose down. How much matters, and when matters nearly as much.
• Movement pushes it either way. Steady effort lowers it; hard, short effort raises it. And the effect lasts long after you stop.

Everything after these three — medication, alcohol, illness, stress, heat, hormones, sleep — is interference on top. Which is why two identical days can give two different numbers, and neither is anybody's fault. Doing the same thing twice and getting different results is one of the most common sources of self-blame; it is also completely expected.

Food: there is no diabetic diet

There is no forbidden list and no special aisle — birthday cake included. What changes is that somebody now has to estimate what is on the plate.

Carbohydrate is the one you dose for. It is fast and large, and it hides in starchy vegetables, milk, beans, juice and sauces — not just bread and sugar.

Fat and protein arrive late. Pizza, poutine, creamy pasta, fried food. A landmark study found a high-fat dinner needed 40% more insulin than a low-fat one with identical carbohydrate — three to six hours later.

Reading a Canadian label. "Carbohydrate" is already the total — never add the sugars line on top. Subtract fibre in full, and about half of any sugar alcohols.

Much more on carbohydrate, labels, the delayed rise, hosting and parties in the Food section.

Insulin: when matters almost as much as how much

It takes time to start. Injected insulin has to be absorbed, and food doesn't wait for it. Diabetes Canada says rapid-acting insulin within 15 minutes of eating; dosing 15 to 20 minutes ahead gives a visibly lower peak, especially at breakfast.

Newer insulins change that. Faster-acting insulin is designed to go in right at the meal, and can be given up to 20 minutes after. So there is no universal rule — which insulin you have decides the timing. Your own timing is a conversation for your diabetes team.

Hosts, take note: give an honest time for food, and update it if it slips. It is one of the most useful things a family member can do tonight.

Movement goes both ways

Steady effort lowers it. Jogging, cycling, swimming, a long walk. Muscles take glucose out of the blood, and injected insulin doesn't switch off the way a pancreas would. The drop often comes within 45 minutes. The starting range for most people is 7 to 10 mmol/L; under 5, take 10 to 20 g of glucose first.

Hard, short effort raises it. Sprints, heavy lifting, intervals, a match. Adrenaline tells the liver to release glucose faster than muscles use it. The pre-game high is usually nerves, and it settles once play starts. Correcting it hard is what causes the crash later.

Understanding that exercise works in two directions removes most of the confusion people bring to it — and with it, a lot of the fear that stops them.

Diabetes Canada recommends 150 minutes a week, spread over at least three days, plus resistance work twice a week. Don't train with ketones at or above 1.5, or within 24 hours of a severe low.

The session ends. The risk doesn't.

Just 45 minutes of activity brings 7 to 11 hours of raised hypo risk afterwards, and insulin sensitivity stays up for as long as 24 hours. That is why exercise after 4pm so often becomes a problem at 2am.

• Drop the overnight basal by about 20%. This is the best-evidenced single move after afternoon or evening activity — agree the details with your team.
• A bedtime snack is not enough on its own. It helps for about eight hours; the basal change is what covers the rest.
• Or simply train earlier. Forty-five minutes at midday doesn't carry the same overnight risk — reassuring for school sport.

Starting glucose, insulin reductions, fuelling, competition nerves, kit and what coaches need are all covered in the Movement section.