Journal of Exercise & Organ Cross Talk
Journal of Eexercise & Organ Cross Talk

Effects of eight weeks of resistance training and vitamin D supplementation on insulin resistance, glycemic control, and inflammatory markers in men with type 2 diabetes: A single blind randomized controlled trial

Articles in Press

Document Type : Original Article

Authors

Sepideh Salimi 1
SeyedSepehr Mousavi 1
Asal Mohammadi 1
Mohammad Hadi Pourramezan 2
Sara Yazdan mehr 1
Anahita Sarrafpour Habibi 1

1 Department of Physical Education and Sport Sciences, SR.C., Islamic Azad university, Tehran, Iran.

2 Department of Exercise Physiology, Sport Sciences Research Institute, Tehran, Iran.

10.22122/jeoct.2026.583128.1205
Abstract
This study aimed to investigate the effects of eight weeks of resistance training (Ex), vitamin D supplementation (VD), and their combination (VD+Ex) on insulin resistance (HOMA IR), glycemic control (HbA1c, fasting glucose), inflammatory markers (interleukin 6 [IL 6] and C reactive protein [CRP]), and anthropometric measures in men with T2DM. In this single blind randomized controlled trial, 40 men with T2DM (aged 40–55 years) were randomly allocated into four groups (n=10 each): placebo control (PI), vitamin D supplementation (2000 IU/day, VD), resistance training (three sessions/week, 60–70% of 1RM, progressive overload, Ex), and combined VD+Ex. All participants maintained their usual diet, lifestyle, and anti-diabetic medications. Fasting blood samples were collected pre and post intervention to measure serum glucose, insulin, 25 hydroxy vitamin D, IL 6, and CRP. HOMA IR was calculated. Post hoc analysis showed that the Ex group had significantly lower HOMA IR than the placebo group (p=0.002), and the VD+Ex group had significantly lower HOMA IR compared to both placebo (p<0.001) and VD alone (p=0.001). The comparison between VD+Ex and Ex was not statistically significant (p>0.05). No significant difference in HbA1c was observed (p=0.210). For body fat percentage, both Ex (p=0.043) and VD+Ex (p<0.001 vs. placebo;p=0.009 vs. VD) showed significant reductions. IL 6 levels were significantly lower in the Ex and VD+Ex groups compared to placebo and VD groups (p<0.001 for both). No significant changes were found in CRP levels (p=0.078). The combination of resistance training and vitamin D did not provide additional statistically significant benefits over resistance training alone for any outcome, including HOMA IR, body fat percentage, or IL 6.

What is already known on this subject?

Type 2 diabetes involves insulin resistance and chronic inflammation, with high IL‑6 and CRP predicting worse outcomes. Resistance training improves glycemic control and insulin sensitivity, but its effect on inflammatory markers is inconsistent. 

 

What this study adds?

This four‑arm RCT in middle‑aged men with T2DM compared resistance training, vitamin D (2000 IU/day), their combination, and placebo. Eight weeks of training (but not vitamin D) significantly reduced HOMA‑IR and IL‑6; the combination showed a numerically greater HOMA‑IR reduction, suggesting a possible additive effect. Neither intervention altered HbA1c or CRP in this short period, indicating longer trials are needed.

Keywords

Type 2 diabetes
Resistance training
Vitamin D supplementation
Insulin resistance
Interleukin 6
HOMA IR
Subjects

Acknowledgements

None.

Funding

None.

Data availability

The data that support the findings of this study are available from the corresponding author upon reasonable request.

Compliance with ethical standards

Conflict of interest The authors declare that there is no conflict of interest in the present research.

Ethical approval All procedures were performed in accordance with the ethical standards of the Declaration of Helsinki and its later amendments.

Informed consent Performed. 

Author contributions 

Conceptualization: S.S., Methodology: S.S.M., Software: A.M., Validation: M.H.P.,; Formal analysis: S.Y.M.,; Investigation: A.Sh.,; Resources: M.H.P.,; Data curation: M.H.P.,; Writing - original draft: M.H.P.,; Writing–review & editing A.M.,; Visualization: S.S.,; Supervision: M.H.P.; Project administration: M.H.P.; Funding acquisition: M.H.P.      

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Journal of Exercise & Organ Cross Talk

Articles in Press, Accepted Manuscript
Available Online from 01 September 2026

  • Receive Date 24 April 2026
  • Revise Date 06 June 2026
  • Accept Date 09 June 2026

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