More exercise, better blood sugar? In 14 trials of children with type 1 diabetes, the middle dose did best — and the most active groups gained least

Parents of children with type 1 diabetes hear the same advice again and again: keep them active. What they rarely get is a number. How much activity, and does more always help? A systematic review and meta-analysis published in Frontiers in Nutrition on 28 October tried to put a dose on it.

The researchers gathered 14 randomised controlled trials, published between 1984 and 2025, that compared an exercise programme with routine care in children and teenagers aged 5 to 18. Together they involved 543 young people, with an average age of about 13, an average of five years since diagnosis and an average starting HbA1c of 8.2%. The programmes ranged widely: aerobic games in the United States, Pilates-style core training in Turkey, daily yoga in India, small-sided recreational football in Saudi Arabia and machine strength training in Austria, among others.

Taken together, exercise lowered HbA1c, the blood test that reflects average glucose over the previous two to three months, by 0.83 percentage points compared with usual care. Fasting blood glucose fell by about 41 mg/dL in the six comparisons that reported it, and daily insulin needs dipped slightly, by 0.16 units per kilogram of body weight. Time spent in the target glucose range, measured by sensor in only three comparisons, did not change significantly.

The new part is the dose. The team turned each programme into MET-minutes a week, multiplying how hard the activity was by how long each session lasted and how often it happened. Programmes in the moderate band, 600 to 1,200 MET-minutes a week (roughly three brisk 45-minute sessions), showed the largest average HbA1c drop, 1.21 points. Programmes below 600 showed a smaller, non-significant fall of 0.50 points, and the three high-dose comparisons above 1,200 showed only 0.30 points.

Before anyone reads that as 'too much exercise is bad', the authors themselves urge caution. The test for a real difference between the three dose groups was not statistically significant, the high-dose group rested on just three comparisons, and the studies differed in length, setting and the children taking part. Half the trials were rated at low risk of bias, six raised some concerns and one was rated high risk, and the funnel plot hinted that small trials with unremarkable results may never have been published. The MET values were also estimated by the reviewers from what each paper described, not measured.

What holds up is the broader message: regular, structured activity seems to help young people with type 1 diabetes keep their glucose steadier, and a sensible, sustainable routine may be enough to see a benefit. The dose question is still open. Any change to a child's exercise plan works best alongside their diabetes team, who can help adjust insulin and snacks around activity to avoid low blood sugar.