What exercise is worth, and how much to do

This page answers the honest question: what does being active actually buy a person with type 1, what doesn't it do, and what does it cost? It ends with how much activity Diabetes Canada recommends.

What it actually buys you

That figure needs care. It comes from an observational cohort (FinnDiane), so it shows a strong association, not proof of cause. Reverse causation is plausible: people who are already sicker tend to move less. It is a striking number, but it should be read as "active people did much better", not "exercise halves your risk".

The benefits with the best support:

• Cardiovascular fitness. This is the most reliably proven benefit. Heart disease is the leading cause of death in type 1, and fitness is the lever with the best evidence behind it.
• Less insulin, better cholesterol. Total daily insulin needs fall consistently across studies. Total cholesterol improves; the individual fractions are less consistent.
• Fewer complications. Active adults with type 1 have less retinopathy and less protein in the urine. Regular aerobic exercise may delay nerve damage.
• Muscle, bone and mood. Strength, bone density and reported wellbeing are on the benefit list in every guideline.

Exercise is not an A1C drug. Do it anyway.

It is worth being straight about this, because people who are told exercise will fix their A1C — and then watch it not move — often conclude the whole thing was a lie.

• In children and teenagers, most evidence points to a modest A1C drop of roughly 0.3 to 0.5%.
• In adults, the effect is small and inconsistent. The best-known meta-analysis found none at all. Newer pooled analyses do find around half a percentage point, and more when the exercise prescription was properly followed.

Diabetes Canada says it plainly: unlike in type 2, most trials in adults with type 1 have not shown a glycemic benefit.

Better numbers and more lows — both are true

In the T1DEXI study of 497 adults with type 1, days with exercise had 76% time in range, against 70% on sedentary days, and less time running high.

The same exercise days also had more time below range: a low on 47% of exercise days, against 40% of rest days.

So nobody should promise you that exercise is free. It costs some lows. Those lows are manageable, and the rest of this section is about how. The benefit is real, and it is worth the management.

One reassuring detail: across the whole study there were three severe low events — none of them on an exercise day or the day after.

How much, according to Diabetes Canada

The two-days-in-a-row rule is the one people miss. It exists because the boost in insulin sensitivity from exercise fades within roughly 48 hours.

Resistance training, twice a week. Three times is better, and it comes in addition to the aerobic work, not instead of it. Start with one set of 15 to 20 repetitions at a moderate weight and build from there.

Break up sitting. Get up briefly every 20 to 30 minutes. This is a separate recommendation from the 150 minutes, and it is an easier place to start.

Children: 60 minutes a day. Mostly aerobic, with vigorous activity and muscle- and bone-strengthening activity on at least three days a week.

If you're starting from nothing

Only about 30% of adults with type 1 reach 150 minutes a week. If that feels far away, keep this in mind: the gap between zero and something is worth more than the gap between 100 and 150. Start where you are.