Journal of health research in community

Introduction
Insulin resistance and pancreatic β-cell dysfunction elevate blood glucose levels and further drive the pathogenesis of type 2 diabetes [1]. Chronic hyperglycemia, as one of the principal consequences of insulin resistance, is a major driver of reactive oxygen species production. Elevated blood glucose leads to excessive free radical production through physiological pathways in the body. The imbalance between the production of reactive oxygen free radicals and the antioxidant defense system’s capacity to neutralize them is defined as oxidative stress [2]. Oxidative stress in diabetes mellitus has several adverse effects on cellular physiology. This is particularly hazardous for the islets of Langerhans because they possess one of the lowest levels of intrinsic antioxidant defenses among body tissues [3]. The most notable manifestations are an increase in the concentration of malondialdehyde (MDA), a marker of oxidative stress, and a decrease in superoxide dismutase (SOD) concentration. These changes impair pancreatic β-cell function and promote peripheral insulin resistance, ultimately contributing to diabetes [4]. 
Alongside exercise training, the use of natural bioactive compounds has also attracted attention as a complementary strategy in diabetes management. For years, researchers have focused on identifying plant derived antioxidant compounds with fewer side effects. One such compound is gamma-oryzanol (γ-Oz), a bioactive compound extracted from rice bran. Owing to its prominent antioxidant and anti-inflammatory properties, it has been recognized as an effective agent for improving obesity-related metabolic disorders, including hyperlipidemia, insulin resistance, and type 2 diabetes [5, 6]. 
Although the separate positive effects of combined training and gamma-oryzanol supplementation on oxidative stress and glycemic indices have been confirmed, no study to date has examined the synergistic effects of these two interventions on the variables of interest in this study. Therefore, the present study was designed and conducted to investigate the effect of combined training along with gamma-oryzanol supplementation on oxidative stress, antioxidant capacity, glycemic indices, and insulin resistance in men with type 2 diabetes.

Methods
his randomized clinical trial included 30 men with type 2 diabetes, aged 45–60 years. Participants were purposively selected and divided into three groups: (1) combined training + placebo (CT+P), (2) combined training + gamma-oryzanol supplementation (CT+S), and (3) a control group. Inclusion criteria included stable glycemic status and no regular physical activity in the preceding six months. All participants had been receiving stable pharmacological treatment with metformin, 500–1000 mg/day, for at least 3 months before enrollment. 
The combined training program consisted of 3 sessions per week for 8 weeks. Each session included resistance exercises (40–70% of one-repetition maximum) and endurance exercises (50–70% of heart rate reserve) [7]. The supplement group (CT+S) received 600 mg of gamma-oryzanol daily [8], while the CT+P group received a placebo. Fasting blood samples were collected 48 hours before the intervention began and 48 hours after the final training session to avoid the acute effects of exercise. Biochemical assays were performed for FBG, insulin, HbA1c, MDA, SOD, and TAC. Data were analyzed using a two-way (group×time) repeated-measures ANOVA at a significance level of P<0.05. 

Results
Statistical results showed significant improvement in metabolic and oxidative markers in both intervention groups (CT+P and CT+S) compared to the control group (P<0.05). Specifically, fasting blood glucose (FBG), insulin levels, and the insulin resistance index (HOMA-IR) showed marked reductions in both training groups. Additionally, glycated hemoglobin (HbA1c), as a key indicator of long-term blood glucose control, decreased significantly after 8 weeks of intervention. 
Regarding oxidative stress markers, MDA levels, which indicate lipid peroxidation, decreased in both training groups relative to the control group. In contrast, SOD and TAC levels, which reflect the body’s antioxidant defense capacity, increased significantly in the intervention groups. However, no statistically significant difference was observed in the direct comparison between the CT+P and CT+S groups (P>0.05). These findings indicate that, although exercise training and its combination with the supplement were superior to the control condition, adding gamma-oryzanol over the 8-week period did not produce a significant additive effect on these specific variables. 

Conclusion
Fasting blood glucose, insulin, and HOMA-IR were significantly reduced in both CT+P and CT+S groups. However, there was no significant difference between the two intervention groups. These findings suggest that combined exercise training was probably the main factor contributing to improved blood glucose levels in this study and that gamma-oryzanol supplementation had no effect. Resistance training increases protein synthesis and glucose uptake through the IGF-1/PI3K/AKT/mTOR pathway, while endurance training primarily improves mitochondrial biogenesis and lipid oxidation through the AMPK/SIRT1/PGC-1α pathway and exerts immune-modulating effects by suppressing pro-inflammatory cytokines, such as TNF-α while increasing anti-inflammatory myokines, such as IL-6. These mechanisms plausibly explain the improvements in blood glucose and oxidative stress observed in both training groups, regardless of supplementation. Gómez-Cabrera et al. reported that exogenous antioxidant supplementation may partially attenuate the physiological adaptations induced by exercise training and disrupt adaptive redox signaling pathways because reactive oxygen species produced during exercise act as signaling molecules necessary for mitochondrial biogenesis and the upregulation of antioxidant enzymes. The absence of a significant synergistic effect between gamma-oryzanol and exercise training in this study warrants further consideration. Although gamma-oryzanol possesses antioxidant properties, the dosage administered (600 mg/day) and the duration of the intervention (8 weeks) were likely insufficient to produce additional effects beyond the powerful physiological adaptations induced by exercise training. It is possible that exercise training acted as the primary driver of metabolic and oxidative improvements, overshadowing the supplement’s small, gradual effects. Future research should consider longer intervention periods or different dosages to fully understand the interaction between antioxidant supplementation and exercise-induced metabolic adaptations in diabetic populations.

Ethical Considerations
Compliance with ethical guidelines
This study was approved by the Ethics Committee of the Sport Sciences Research Institute (Code: IR.SSRC.REC.1404.136) and was registered by the Iranian Registry of Clinical Trials (ID: IRCT20251205068219N1). 

Funding
This article was extracted from Mehdi Rostamizadeh's doctoral thesis in Sports Physiology at the Faculty of Sports Sciences, Urmia University. This research did not receive any specific grant from funding agencies in the public, commercial, or not-for profit sectors.

Authors contributions
Software, formal analysis, investigation, resources, data curation, original draft preparation, review & editing: Mehdi Rostamizadeh and Kazem Khodaei; Conceptualization and methodology: Kazem Khodaei and Hamed Hamishehkar; Supervision: All authors; Project administration: Kazem Khodaei. All authors read and approved the final version of the manuscript.

Conflicts of interest
The authors declared no conflicts of interest

Acknowledgents
The authors would like to thank all the students who participated in this study for their cooperation.

References

1. Afshounpour MT, Habibi A, Ranjbar R. Impact of combined exercise training on plasma concentration of apelin, resistin and insulin resistance in patients with type 2 diabetics’ male. Hormozgan Med J. 2016; 20(3):158-69. [Link]
2. Dludla PV, Mabhida SE, Ziqubu K, Nkambule BB, Mazibuko-Mbeje SE, Hanser S, et al. Pancreatic β-cell dysfunction in type 2 diabetes: Implications of inflammation and oxidative stress. World J Diabetes. 2023; 14(3):130-46. [DOI:10.4239/wjd.v14.i3.130] [PMID]
3. Caturano A, D’Angelo M, Mormone A, Russo V, Mollica MP, Salvatore T, et al. Oxidative Stress in Type 2 Diabetes: Impacts from Pathogenesis to Lifestyle Modifications. Curr Issues Mol Biol. 2023; 45(8):6651-66. [DOI:10.3390/cimb45080420] [PMID] [PMCID]
4. Tiwari BK, Pandey KB, Abidi AB, Rizvi SI. Markers of Oxidative Stress during Diabetes Mellitus. J Biomark. 2013; 2013:378790. [DOI:10.1155/2013/378790] [PMID] [PMCID]
5. Qiu C, Li S, Jia S, Yu F, Wei C, Wang X, Guo B. The effects of exercise on oxidative stress MDA and SOD in patients with type 2 diabetes: A systematic review and meta-analysis. Peer J. 2025; 13:e19814. [DOI:10.7717/peerj.19814] [PMID] [PMCID]
6. Shodehinde SA, boh GO. Antioxidant properties of aqueous extracts of unripe Musa paradisiaca on sodium nitroprusside induced lipid peroxidation in rat pancreas in vitro. Asian Pac J Trop Biomed. 2013; 3(6):449-57. [DOI:10.1016/S2221-1691(13)60095-7] [PMID] [PMCID]
7. Salgueiro AC, Leal CQ, Bianchini MC, Prado IO, Mendez AS, Puntel RL, et al. The influence of Bauhinia forficata Link sub sp. pruinosa tea on lipid peroxidation and non-protein SH groups in human erythrocytes exposed to high glucose concentrations. J Ethnopharmacol. 2013; 148(1):81-7. [DOI:10.1016/j.jep.2013.03.070] [PMID]
8. Bandeira Sde M, Guedes Gda S, da Fonseca LJ, Pires AS, Gelain DP, Moreira JC, et al. Characterization of blood oxidative stress in type 2 diabetes mellitus patients: Increase in lipid peroxidation and SOD activity. Oxid Med Cell Longev. 2012; 2012:819310. [DOI:10.1155/2012/819310] [PMID] [PMCID]
9. Idan HH, Mohamoud HG. The Total Antioxidant Capacity and its Relationship with Atherosclerosis Risk Factors in a Sample of Iraqi Individuals with Type 2 Diabetes Mellitus. J Fac Med Baghdad. 2024; 66(3):357-62. [DOI:10.32007/jfacmedbaghdad.6632334]
10. Davari S, Talaei SA, Alaei H, Salami M. Probiotics treatment improves diabetes-induced Impairment of synaptic activity and cognitive function: Behavioral and electrophysiological proofs for Microbiome-gut-brain axis. Neuroscience. 2013; 240:287-96. [DOI:10.1016/j.neuroscience.2013.02.055] [PMID]
11. Chang S, Liu H. Effects of combined resistance training and Tai Chi on oxidative stress, blood glucose and lipid metabolism and quality of life in elderly patients with type 2 diabetes mellitus. Res Sports Med. 2024; 32(5):871-84. [DOI:10.1080/15438627.2024.2349521] [PMID]
12. Zhang Q, Guo Y, Zhang H, Xu W, Yin L. Effects of aerobic, resistance, interval, and combined training on glucose metabolism in older adults: insights into type, dose, and mechanism. Front Physiol. 2025; 16:1702669. [DOI:10.3389/fphys.2025.1702669] [PMID] [PMCID]
13. Róvero Costa M, Leite Garcia J, Cristina Vágula de Almeida Silva C, Junio Togneri Ferron A, Valentini Francisqueti-Ferron F, Kurokawa Hasimoto F, et al. Lycopene modulates pathophysiological processes of non-alcoholic fatty liver disease in obese rats. Antioxidants. 2019; 8(8):276. [DOI:10.3390/antiox8080276] [PMID] [PMCID]
14. Ferron AJT, Aldini G, Francisqueti-Ferron FV, Silva CCVA, Bazan SGZ, Garcia JL, et al. Protective effect of tomato-oleoresin supplementation on oxidative injury recoveries cardiac function by improving β-adrenergic response in a diet-obesity induced model. Antioxidants (Basel). 2019; 8(9):368.  [DOI:10.3390/antiox8090368] [PMID] [PMCID]
15. Kozuka C, Sunagawa S, Ueda R, Higa M, Tanaka H, Shimizu-Okabe C, et al. γ-oryzanol protects pancreatic β-cells against endoplasmic reticulum stress in male mice. Endocrinology. 2015; 156(4):1242-50.  [DOI:10.1210/en.2014-1748] [PMID]
16. Kozuka C, Sunagawa S, Ueda R, Higa M, Ohshiro Y, Tanaka H, et al. A novel insulinotropic mechanism of whole grain-derived γ-oryzanol via the suppression of local dopamine D2 receptor signalling in mouse islet. Br J Pharmacol. 2015; 172(18):4519-34. [DOI:10.1111/bph.13236] [PMID] [PMCID]
17. Wang O, Liu J, Cheng Q, Guo X, Wang Y, Zhao L, et al. Effects of ferulic acid and γ-oryzanol on high-fat and high-fructose diet-induced metabolic syndrome in rats. PLoS One. 2015; 10(2):e0118135. [DOI:10.1371/journal.pone.0118135] [PMID] [PMCID]
18. Bhaskaragoud G, Chatterjee P, Kumar GS. Effect of oryzanol concentrate on hypolipidemic properties and antioxidant enzymes of liver in high fat fed and low STZ induced-male Wistar rats. Biomedicine. 2020; 40(1):25-31. [Link]
19. Mattei L, Francisqueti-Ferron FV, Garcia JL, Ferron AJT, Silva CCVA, Gregolin CS, et. al. Antioxidant and anti-inflammatory properties of gamma- oryzanol attenuates insulin resistance by increasing GLUT- 4 expression in skeletal muscle of obese animals, Mol Cell Endocrinol. 2021; 537:111423. [DOI:10.1016/j.mce.2021.111423] [PMID]
20. Mohammadi A, Bijeh N, Moazzami M, Kazem Khodaei, Rahimi N. Effect of exercise training on spexin level, appetite, lipid accumulation product, visceral adiposity index, and body composition in adults with type 2 diabetes. Biol Res Nurs. 2022; 24(2):152-62.  [DOI:10.1177/10998004211050596] [PMID]
21. Ghiyami SH, Afroundeh R, Pourvaghar MJ, Sadeghi A, Katebi L. [The Effect of 8 Weeks of Combined Exercises with Supplemental Consumption of Mulberry Leaf Extract on the Serum Levels of Fibroblast Growth Factor 21, Glucose and Insulin in Elderly Men with Type 2 Diabetes (Persian)]. Complement Med J. 2023; 12(4):1-12. [DOI:10.61186/cmja.12.4.1]
22. Eslami S, Esa NM, Marandi SM, Ghasemi G, Eslami S. Effects of gamma oryzanol supplementation on anthropometric measurements & muscular strength in healthy males following chronic resistance training. Indian J Med Res. 2014; 139(6):857-63. [PMID]
23. Silva FM, Duarte-Mendes P, Teixeira AM, Soares CM, Ferreira JP. The effects of combined exercise training on glucose metabolism and inflammatory markers in sedentary adults: A systematic review and meta-analysis. Sci Rep. 2024; 14(1):1936. [DOI:10.1038/s41598-024-51832-y] [PMID]
24. Wan Y, Su Z. The Impact of Resistance Exercise Training on Glycemic Control Among Adults with Type 2 Diabetes: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Biol Res Nurs. 2024; 26(4):597-623.[DOI:10.1177/10998004241246272] [PMID]
25. Kazeminasab F, Moien A, Pourvaghar MJ. [The Impacts of Exercise Training on Serum Irisin Levels and Glycemic Indices in Type 2 Diabetes Patients: A Systematic Review and Meta-Analysis (Persian)]. Razi J Med Sci. 2025; 32(1):50. [Link]
26. Rahmati M, Shariatzadeh M, Azari N. [The Effects of Endurance Exercise on Some Related Variables of Type II Diabetes: Systematic Review and Meta-Analysis of Studies in Iran (Persian)]. Sport Physiol. 2019; 11(41):81-104. [Link]
27. Vergara Ampuero D, Calquín Lorca ME, Contador Cantillana C, Valenzuela Pérez D, Carrenho Queiroz AC, Alves dos Santos D, et al. The effect of aerobic and concurrent training on cardiovascular and metabolic control in middle-aged type II diabetics. J Phys Educ Sport. 2023; 23(3):631-6. [Link]
28. Zhao X, He Q, Zeng Y, Cheng L. Effectiveness of combined exercise in people with type 2 diabetes and concurrent overweight/ obesity: A systematic review and meta-analysis. BMJ Open. 2021; 11(10):e046252.  [DOI:10.1136/bmjopen-2020-046252] [PMID]
29. Banaei P, Tadibi V, Rahimi M. [Comparing the effect of two protocols concurrent training (strength-aerobic) on fasting blood glucose, glycosylated hemoglobin, high-sensitivity C - reactive protein and insulin resistance in women with type 2 diabetes (Persian)]. Sport Physiol. 2015; 7(25):99-108. [Link]
30. Azamian Jazi A, Shokouhi R. [The effect of an eight week combined exercise training on oxidative stress and lipid peroxidation in postmenopausal women with type 2 diabetes (Persian)]. J Shahid Sadoughi Univ Med Sci. 2016; 24(8):667-78. [Link]
31. Tofighi A, Shirzadfar M, Tolouei Azar J, Jamali Gharakhanlou B. [The Effect of a Period of Functional Exercise with and Without Chlorella Vulgaris Supplement on some Inflammatory, Lipid Peroxidation and Antioxidant Indices in Overweight and Obese Men (Persian)]. Jundishapur J Med Sc. 2024; 23(1):75-88. [DOI:10.32592/JSMJ.23.1.75]
32. Hooshmand B, Attarzade Hosseini SR, Kordi MR, Davaloo T. [The Effect of 8-week Aerobic Exercise with Spirulina Supplementation Consumption on Plasma levels of MDA, SOD and TAC in Men with Type 2 Diabetes (Persian)]. Sport Physiol Manag Investig. 2019; 10(4):139-48.  Link]
33. Attarzadeh Hosseini SR, Moazzami M, Farahati S, Bahremand M, Sadegh Eghbali F. [Effects of high-intensity interval training versus moderate-intensity continuous training on the total antioxidant capacity, malondialdehyde, and superoxide dismutase in obese/overweight middle-aged women (Persian)]. Iran J Endocrinol Metab. 2020; 22(3):207-13. [Link]
34. Radda MI, Omar N, Yusof SFM, Ahmad R, Rohana AJ, Ishak WRW, et al. Effectiveness of gamma-oryzanol in glycaemic control and managing oxidative stress, inflammation, and dyslipidaemia in diabetes: A systematic review of preclinical studies. PeerJ. 2025; 13:e20062. [DOI:10.7717/peerj.20062] [PMID]