Type 2 Diabetes Mellitus (T2DM) is a chronic metabolic disorder characterized by insulin resistance and hyperglycemia, with increasing global prevalence due to sedentary lifestyles and poor dietary habits (1). A growing body of evidence suggests that low-grade systemic inflammation plays a pivotal role in the pathogenesis and progression of T2DM and its associated complications, including cardiovascular disease and nephropathy (2). Inflammatory cytokines such as interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), and C-reactive protein (CRP) have been identified as key biomarkers that reflect the inflammatory status in individuals with T2DM (3).

Exercise is widely recognized as a cornerstone in the management of T2DM. Regular physical activity improves glycemic control, insulin sensitivity, lipid profiles, and overall metabolic health (4). Moreover, exercise has demonstrated significant potential in modulating inflammatory responses, thereby mitigating the risks associated with chronic inflammation in diabetic patients (5). Both aerobic and resistance exercises have been studied for their anti-inflammatory effects; however, the comparative effectiveness of these exercise modalities on specific inflammatory biomarkers remains an area of active investigation.

Aerobic exercise, typically involving rhythmic and continuous activities such as walking, cycling, or swimming, has been shown to reduce CRP levels and improve endothelial function (6). On the other hand, resistance training, which involves muscle strengthening through weight lifting or resistance bands, has demonstrated promising results in lowering IL-6 and TNF-α, potentially through muscle-induced anti-inflammatory myokine release (7). Despite these findings, there is limited consensus on which exercise modality offers superior anti-inflammatory benefits for T2DM patients.

Therefore, this study aims to compare the effects of resistance versus aerobic exercise on key inflammatory biomarkers—CRP, IL-6, and TNF-α—in patients with T2DM, to provide evidence-based recommendations for exercise prescription in diabetes management.

Study Design and Participants

This randomized controlled trial was conducted over a period of 12 weeks at a tertiary care fitness and diabetes research facility. A total of 60 patients diagnosed with Type 2 Diabetes Mellitus (T2DM) were recruited through outpatient referrals and screened for eligibility. Inclusion criteria included adults aged 40–60 years with a confirmed diagnosis of T2DM for at least one year, HbA1c between 6.5% and 9.0%, and sedentary lifestyle history. Participants with acute or chronic infections, cardiovascular complications, renal dysfunction, or those on anti-inflammatory medication were excluded.

Randomization and Group Allocation

Participants were randomly assigned using a computer-generated sequence into two groups: Resistance Exercise Group (REG, n=30) and Aerobic Exercise Group (AEG, n=30). Both groups underwent supervised exercise sessions three times per week for 12 weeks.

Intervention Protocols

• Resistance Exercise Group (REG): Participants performed resistance training targeting major muscle groups using weight machines and free weights. Exercises included leg press, chest press, lat pull-down, leg curls, and shoulder press. Each session consisted of 3 sets of 8–10 repetitions at 60–70% of one-repetition maximum (1RM), progressively increased every two weeks.
• Aerobic Exercise Group (AEG): Participants engaged in moderate-intensity aerobic activities such as brisk walking and cycling on stationary bikes. Each session lasted 45 minutes, maintaining 60–75% of their maximum heart rate, monitored using heart rate monitors.

Biochemical Assessments

Venous blood samples were collected at baseline and after 12 weeks of intervention. Samples were centrifuged and stored at –80°C until analysis. Inflammatory biomarkers including C-reactive protein (CRP), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-α) were measured using commercially available enzyme-linked immunosorbent assay (ELISA) kits, following manufacturer instructions.

Statistical Analysis

Data were analyzed using SPSS software version 25.0. Continuous variables were expressed as mean ± standard deviation. Paired t-tests were used to compare pre- and post-intervention values within each group, and unpaired t-tests were used for between-group comparisons. A p-value of <0.05 was considered statistically significant.

A total of 60 participants completed the 12-week intervention without any dropouts. The baseline characteristics including age, duration of diabetes, and HbA1c were comparable between the Resistance Exercise Group (REG) and the Aerobic Exercise Group (AEG), with no statistically significant differences observed (p>0.05).

Changes in Inflammatory Biomarkers

Post-intervention analysis revealed significant reductions in inflammatory biomarkers in both groups, with greater improvement noted in the resistance training group.

As shown in Table 1, the mean CRP level in the REG decreased from 5.8 ± 1.2 mg/L at baseline to 3.4 ± 1.0 mg/L after 12 weeks (p<0.001), while in the AEG, CRP reduced from 5.6 ± 1.3 mg/L to 4.0 ± 1.1 mg/L (p=0.002). Between-group comparison showed no significant difference in CRP reduction (p=0.078).

Table 1: Comparison of CRP Levels Before and After Intervention

In terms of IL-6, Table 2 illustrates a significant reduction in the REG from 8.2 ± 1.5 pg/mL to 5.1 ± 1.1 pg/mL (p<0.001), compared to a reduction from 8.0 ± 1.4 pg/mL to 6.0 ± 1.2 pg/mL in the AEG (p=0.004). The between-group comparison showed a statistically significant difference in IL-6 reduction favoring REG (p=0.03).

Table 2: Comparison of IL-6 Levels Before and After Intervention

As indicated in Table 3, TNF-α levels also declined more significantly in the REG, dropping from 6.9 ± 1.3 pg/mL to 4.6 ± 1.0 pg/mL (p<0.001), while in the AEG, it decreased from 6.8 ± 1.4 pg/mL to 5.2 ± 1.1 pg/mL (p=0.006). The between-group difference was significant (p=0.04), suggesting superior anti-inflammatory response with resistance training.

Table 3: Comparison of TNF-α Levels Before and After Intervention

Overall, both exercise modalities led to a reduction in inflammatory markers; however, resistance exercise showed more pronounced improvements in IL-6 and TNF-α (Tables 2 and 3).

The findings of this study demonstrate that both resistance and aerobic exercise significantly reduce inflammatory biomarkers—CRP, IL-6, and TNF-α—in patients with Type 2 Diabetes Mellitus (T2DM). However, resistance exercise produced a more pronounced reduction in IL-6 and TNF-α levels when compared to aerobic training, suggesting its potential superiority in modulating systemic inflammation in this population.

Chronic inflammation is a known contributor to insulin resistance and the progression of T2DM and its complications (1). Elevated levels of pro-inflammatory cytokines such as IL-6 and TNF-α impair insulin signaling and beta-cell function (2,3). Therefore, strategies that mitigate inflammation could have beneficial effects on glycemic control and disease outcomes.

In the present study, resistance training resulted in a significant reduction in TNF-α levels, aligning with previous findings that suggest strength training induces the release of anti-inflammatory myokines such as IL-10 and IL-1 receptor antagonist (4,5). These cytokines are believed to counteract the effects of TNF-α, thus reducing systemic inflammation (6). In contrast, aerobic exercise is traditionally associated with improved cardiovascular fitness and moderate reductions in inflammatory markers, largely through fat loss and increased antioxidant activity (7,8).

The greater reduction in IL-6 observed in the resistance training group may also be attributed to enhanced muscle mass and improved glucose uptake, which reduce the pro-inflammatory state associated with insulin resistance (9,10). Previous studies have shown that muscle contractions stimulate the release of IL-6 from muscle fibers in an anti-inflammatory role, independent of TNF-α elevation (11). This contrasts with chronically elevated IL-6 from adipose tissue, which contributes to inflammation and metabolic dysregulation (12).

CRP, an acute-phase reactant produced in response to IL-6, decreased significantly in both groups without a significant difference between them. This suggests that both exercise modalities can lower systemic inflammation through different physiological pathways (13). Although weight loss was not directly measured in this study, previous literature indicates that reduced visceral fat through aerobic training also correlates with lower CRP levels (14).

These findings have practical implications for diabetes management. While aerobic exercise is commonly prescribed, incorporating resistance training may yield greater anti-inflammatory benefits and improve overall metabolic health. Moreover, resistance training is often better tolerated in older adults or those with mobility issues, making it a feasible long-term intervention (15).

However, this study is not without limitations. The relatively short intervention duration, small sample size, and lack of dietary control may have influenced the results. Additionally, body composition changes were not assessed, which could have provided further insight into the mechanisms of inflammation reduction. Future studies with larger cohorts and longer follow-up periods are warranted to validate these findings and explore the underlying mechanisms more comprehensively.

Both resistance and aerobic exercise significantly reduce inflammatory biomarkers in patients with Type 2 Diabetes Mellitus. However, resistance training shows greater efficacy in lowering IL-6 and TNF-α levels, highlighting its potential as a superior strategy for inflammation management in diabetic care.

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