- βResistance exercise caused the smallest blood sugar drop (9 mg/dL), making it safer for those prone to hypoglycemia
- βAll exercise types improved 24-hour time in range from 70% to 76%, meeting ADA targets
- βFindings applied equally across closed-loop pumps, standard pumps, and multiple daily injections
| Country | Canada |
| Journal | Diabetes care |
| Year | 2023 |
| Authors | Riddell, Li, Gal |
| PMID | 36795053 |
A study from Canada offers some of the most practical, real-world guidance yet for adults living with type 1 diabetes who want to exercise safely β and it delivers good news alongside some important cautions.
Researchers at York University's Muscle Health Research Centre in Toronto conducted the Type 1 Diabetes Exercise Initiative (T1DEXI), enrolling 497 adults with type 1 diabetes across the United States and Canada. Rather than a controlled lab setting, participants exercised at home over four weeks β making the findings especially relevant to everyday life.
What the Researchers Did
Participants were randomly assigned to complete six structured sessions of one of three exercise types: aerobic (such as walking or cycling), interval (alternating high and low intensity), or resistance (strength training). They tracked food intake, insulin dosing, heart rate, and blood sugar using a smartphone app and continuous glucose monitors (CGMs). The group included users of closed-loop insulin pumps, standard pumps, and multiple daily injections (MDI).
The average participant was 37 years old with a well-controlled HbA1c of 6.6% β a population that mirrors many motivated, health-conscious Americans with type 1 diabetes.
Key Findings: Not All Exercise Is Equal
All three exercise types caused blood sugar to drop during the workout, but the degree varied significantly:
- Aerobic exercise: Average drop of 18 mg/dL
- Interval exercise: Average drop of 14 mg/dL
- Resistance exercise: Average drop of 9 mg/dL β the smallest decline
This pattern held true regardless of how participants delivered their insulin β an important finding for the diverse range of insulin management strategies used by American patients.
The 24-Hour Benefit
Perhaps the most encouraging finding: on days when participants completed structured exercise, their time in range (TIR) β the percentage of time blood sugar stayed between 70β180 mg/dL β improved meaningfully. Exercise days averaged 76% time in range, compared to 70% on non-exercise days. The American Diabetes Association currently recommends a TIR target of at least 70% for most adults with type 1 diabetes, meaning exercise helped many participants meet or exceed this benchmark.
However, exercise days also slightly increased time below range (below 70 mg/dL), underscoring the need for careful monitoring around workouts.
Why This Matters for US Patients
For Americans managing type 1 diabetes, this Canadian real-world study provides actionable guidance that lab-based research often can't:
- Resistance training may be safer for those prone to exercise-induced hypoglycemia, since it causes the smallest blood sugar drop.
- Interval training offers a middle ground β meaningful glucose reduction with less hypoglycemia risk than steady aerobic exercise.
- Any structured exercise improves your daily TIR, helping you meet ADA targets β a strong motivator to stay active.
- The findings apply whether you use a closed-loop pump, standard pump, or injections β covering the full spectrum of American insulin delivery methods.
- Always discuss pre-exercise snack strategies and insulin adjustments with your care team, especially given the increased low blood sugar risk noted in this study.
Source: Riddell, Li, Gal et al. "Examining the Acute Glycemic Effects of Different Types of Structured Exercise Sessions in Type 1 Diabetes in a Real-World Setting: The Type 1 Diabetes and Exercise Initiative (T1DEXI)." Diabetes Care, 2023. DOI: 10.2337/dc22-1721. PMID: 36795053.