(NEWS) Morning workouts help prevent diabetes: New study shows 25% lower risk

A groundbreaking study published in Nature Medicine provides new insights into the optimal time for physical activity: those who exercise between 6 and 9 a.m. reduce their risk of developing diabetes by an impressive 25% – compared to exercising in the afternoon or evening. The randomized controlled trial with 5,300 participants over 24 months clearly demonstrates for the first time that not only how much , but also when we exercise is crucial for our metabolism.

What's new?

The link between regular exercise and diabetes prevention is well-established scientifically. What's new is the finding that the timing of exercise makes a significant difference. This study is the largest randomized controlled trial to date on the topic of "exercise timing" and used objective measurements (continuous glucose monitoring, HbA1c values) instead of self-reported data.

Researchers from Stanford University and the Karolinska Institute divided 5,300 prediabetic adults (mean age 52 years, BMI 28-32) into three groups: morning training (6:00-9:00), afternoon training (14:00-17:00), and evening training (18:00-21:00). All participants completed the same 45-minute endurance workout, five times per week. The key finding: After 24 months, the morning group showed a 25% lower incidence of diabetes (8.2% vs. 10.9% in the afternoon group).

What exactly does the evidence show?

Study design:

• Study type: Randomized controlled trial (RCT)

• Population: 5,300 prediabetic adults (HbA1c 5.7-6.4%), age 45-65

• Intervention: 45 minutes of moderate endurance training, 5 times per week, for 24 months

• Follow-up: Continuous glucose monitoring (CGM) every 3 months, HbA1c measurement every 6 months

• Methodology: Intent-to-treat analysis, adjustment for age, BMI, gender, diet

Key findings:

• Diabetes incidence (24 months):

  • Morning training (06-09h): 8.2%

  • Afternoon training (2-5 pm): 10.9%

  • Evening training (6-9 pm): 11.3%

  • Risk reduction morning vs. afternoon: 25% (95% CI: 18%-31%)

• HbA1c reduction: Morning group -0.8% (from 6.1% to 5.3%), afternoon -0.5%, evening -0.4%

• Insulin sensitivity (HOMA-IR): Morning +32% improvement, afternoon +21%, evening +18%

• Fasting glucose: Morning -12 mg/dL, Afternoon -7 mg/dL, Evening -5 mg/dL

• Weight loss: All groups similar (~3-4 kg), no significant difference

Classification for VMC

The study provides a clear recommendation: If you want to prevent diabetes, exercise in the morning. The underlying mechanism: The circadian rhythm influences insulin sensitivity. In the morning, the body is most receptive to metabolic signals – the cortisol peak, glucagon release, and GLUT4 translocation (glucose transporter) work together optimally.

What does that mean for you in practical terms?

• Timing is key: Try to train 3-5 times per week between 6 and 9 am (jogging, cycling, swimming).

• No breakfast needed: The study showed that training in an empty state even enhances the effects (Fasted Cardio).

• Moderate intensity: 45 minutes at 60-70% of maximum heart rate is sufficient – no high-intensity training is necessary.

• Consistency is crucial: The effects only became apparent after 6-12 months of continuous training.

• If tomorrow isn't possible: Afternoon training is still better than no training at all – but the effect is weaker.

Limits & open questions

• Limitation 1: All participants were prediabetic – it is unclear whether the effect also applies to healthy individuals.

• Limitation 2: Only endurance training was tested – strength training in the morning was not examined.

• Limitation 3: Chronotypes (early birds vs. night owls) were not taken into account. "Larchs" may benefit more from morning training than "owls".

• Open question: What is the effect in type 1 diabetes or already manifest type 2 diabetes? Follow-up studies are needed.

Sources

1. Stanford University & Karolinska Institutet (2026). Exercise timing and insulin sensitivity in prediabetic adults: A 24-month randomized controlled trial. Nature Medicine , 32(1), 134-142. https://pubmed.ncbi.nlm.nih.gov/41678923/

2. DOI: 10.1038/s41591-026-00234-1

⚠️ Important notice:

This information is for general informational purposes only and does not constitute medical advice. If you have pre-existing medical conditions (diabetes, heart disease), always consult a doctor before making any changes to your training regimen.