A randomized control trial done in 2019 compared high-intensity interval training (HIT), with moderate continuous aerobic training (MCT) and no exercise (control) (36 participants; mean age 23.5 +/- 6 years) . Baseline VO2peak was similar in all groups, with the largest increase from baseline after HIT (17.6%, p = 0.0001), compared to MCT (3%, p = 0.055) and control (p = 0.63). The study concluded that in patients with type 1 diabetes without microvascular complications, an 8-week HIT program produced greater improvement in physical fitness than MCT at a similar glycaemic control.
A separate systematic review in 2011 of 48 articles found that physical activity (for more than 7 days, irrespective of intensity) improves physical fitness and strength, but did not refer to any specific type of physical activity .
Quality of Evidence
A – High
Strength of Recommendation
1 – Strong recommendation
Physical activity improves physical fitness and strength overall. Compared with other types of training and no exercise, HIT best improves physical fitness.
 Boff W, da Silva AM, Farinha JB, Rodrigues-Krause J, Reischak-Oliveira A, Tschiedel B, Puñales M, Bertoluci MC. Superior Effects of High-Intensity Interval vs. Moderate-Intensity Continuous Training on Endothelial Function and Cardiorespiratory Fitness in Patients With Type 1 Diabetes: A Randomized Controlled Trial. Front Physiol. 2019 Apr 24;10:450. doi: 10.3389/fphys.2019.00450. PMID: 31110479; PMCID: PMC6499209.
 Chimen, M., Kennedy, A., Nirantharakumar, K. et al. What are the health benefits of physical activity in type 1 diabetes mellitus? A literature review. Diabetologia 55, 542–551 (2012). https://doi.org/10.1007/s00125-011-2403-2