The global burden of diabetes mellitus has reached unprecedented levels, posing a major public health challenge worldwide. According to recent estimates, approximately 537 million adults were living with diabetes in 2021, with nearly 90% of these cases attributed to type 2 diabetes mellitus (T2DM). Alarmingly, this number is projected to increase to 643 million by 2030, reflecting a rapid and sustained rise driven by urbanization, sedentary lifestyles, and dietary transitions (1). This escalating prevalence underscores the urgent need for early preventive strategies, particularly in regions with heightened vulnerability.

South Asia represents one such high-risk region, where the epidemiology of diabetes exhibits distinct characteristics. Individuals in this population tend to develop T2DM at a younger age and at comparatively lower body mass index (BMI) and waist circumference than their Western counterparts (2). This phenomenon is often attributed to a higher proportion of visceral adiposity, genetic predisposition, and increased insulin resistance despite lower overall adiposity. Consequently, traditional anthropometric cut-offs may underestimate metabolic risk in this population, necessitating earlier screening and intervention.

Glucose tolerance plays a pivotal role in the diagnosis and progression of T2DM. Impaired glucose tolerance (IGT) represents an intermediate metabolic state between normoglycemia and overt diabetes and is a critical window for intervention. Individuals with IGT are at a significantly increased risk of progressing to T2DM, as well as developing associated complications such as cardiovascular disease. Therefore, identifying and addressing alterations in glucose metabolism at an early stage is essential to curb the growing burden of metabolic disorders.

The increasing prevalence of prediabetes and metabolic syndrome among young adults further amplifies this concern. Sedentary behavior, particularly among urban populations, has been strongly linked to the development of insulin resistance and impaired glucose metabolism. In this context, lifestyle modification emerges as a cornerstone in the prevention and management of T2DM. Among various interventions, physical activity has consistently demonstrated beneficial effects on glycemic control, insulin sensitivity, and overall metabolic health.

Exercise is widely recognized as an effective, non-pharmacological strategy to improve glucose homeostasis. It enhances peripheral glucose uptake by increasing insulin sensitivity in skeletal muscle and promoting glucose transporter type 4 (GLUT4) translocation independent of insulin action. Additionally, regular physical activity contributes to weight management, reduction in visceral fat, and improvement in lipid profiles, thereby mitigating multiple risk factors associated with T2DM (3). These physiological benefits highlight the importance of incorporating structured exercise into daily routines, particularly for individuals at high risk.

Several studies have explored the impact of different exercise intensities on glucose tolerance and metabolic outcomes. High-intensity interval training (HIIT) and vigorous aerobic exercise have shown significant improvements in insulin sensitivity and glycemic control. However, such regimens may not be feasible or sustainable for all individuals, especially those who are sedentary, older, or have comorbid conditions. In contrast, moderate-intensity exercise, such as brisk walking or cycling, offers a more practical and accessible alternative that can be maintained over the long term. (4,5)

Despite the well-established benefits of physical activity, there remains a relative paucity of data focusing specifically on the effects of moderate-intensity exercise in populations from South India who are at risk of developing diabetes. Given the unique metabolic profile and early onset of disease in this group, it is crucial to evaluate interventions that are both effective and culturally acceptable. Moderate-intensity exercise holds particular promise in this regard, as it requires minimal resources, can be easily integrated into daily life, and is suitable for individuals across different age groups and fitness levels.

Furthermore, short-term interventions examining the immediate impact of exercise on glucose tolerance can provide valuable insights into the physiological responsiveness of prediabetic individuals. Such evidence may help reinforce the role of lifestyle modification as a first-line strategy and encourage early adoption of healthy behaviors. If moderate-intensity exercise is shown to significantly improve glucose tolerance even over a brief duration, it could serve as a powerful, low-cost intervention to delay or prevent the onset of T2DM.

In conclusion, the rising global prevalence of T2DM, coupled with the heightened susceptibility observed in South Asian populations, necessitates targeted preventive strategies. Early identification of impaired glucose tolerance and timely implementation of lifestyle interventions are critical in reducing disease progression and associated complications. Moderate-intensity exercise, due to its feasibility and sustainability, represents a promising approach for improving glucose metabolism in at-risk individuals. Further research focusing on this intervention in South Indian populations is warranted to generate context-specific evidence and inform public health strategies aimed at combating the diabetes epidemic.

This cross-sectional study was conducted subsequent to the approval by the Institutional Ethical Committee. The study was conducted in Department of Physiology at Shri Atal Bihari Vajpayee Medical College and Research Institute, Shivajinagar. The collection of blood samples was done in Hematology lab, Department of Physiology.

 All subjects (Students and Outpatient attenders) under age group 18-60, who were willing to take part in this study from areas in and around Shivajinagar were considered as study population. The population were selected according to inclusion and exclusion criteria wherein sedentary overweight healthy individuals (Asia pacific BMI 23-24.9,WHO) including grade 1 obese individuals (Asia pacific BMI 25-29.9, WHO) with no co-morbidities like PCOS, menstrual abnormalities and who are not under any medication. The participants were informed about the study procedure in our understandable language and written informed consent was obtained.

 In the first part of the study, we recruited 104 subjects according to data of previous studies as sample size by simple random sampling and a detailed history of each participant along with height and weight measurements were collected. Subjects who met BMI criteria were asked to report early in the morning in 12-h fasting state. Subsequently, we collected capillary blood samples for assessing fasting blood glucose using Standardized Calibrated Glucometer. The GlucocardTM glucometer was standardized and calibrated by comparing fasting and postprandial blood glucose values with intravenous blood glucose values at medical college & hospital biochemistry lab. We retained the subjects whose fasting blood glucose was under prediabetic range(100-125 mg/dL)(6) and tested their postprandial blood glucose levels after 2-h on the same day.

Prediabetics from the postprandial test(140-199 mg/dL)(6) were followed up the next day to perform oral glucose tolerance test in a 12-h fasting state. OGTT was performed by administering a standard of 75g glucose load. Capillary blood glucose were sampled using glucometer at each half an hour interval for two hours. OGTT meeting the criteria of prediabetics were followed up. (Pre-diabetic OGTT after 2 hours=140-199 mg/dl(6)). Selected participants performed moderate intensity exercise by brisk walking for 30 min/day for 7 consecutive days. Brisk walking at a rate of 3-4.5 mph (~3.2km/day) is considered under moderate-intensity physical activity(7). We tracked the physical activity of each subject daily by monitoring the Pedometer app. The subjects were instructed to follow their usual diet during the study. After a period of one week, we conducted oral glucose tolerance test using glucometer by collecting the capillary blood samples. We tabulated the data obtained from each individual and checked for the effect on glucose tolerance.

Microsoft Excel and statistical software graph pad was used for data analysis. Statistical analysis was done using students paired T-test for comparison. Values of P ≤0.05 were considered statistically significant.

We studied a series of 104 individuals, aged between 18-40 years, tabulated and graphed the results. The incidence of prediabetes using fasting blood glucose was found to be 27%. 36% among these i.e.10 individuals also had elevated postprandial blood glucose level.

Fasting and postprandial blood glucose concentrations of these individuals averaged 125.5±16.1 and 159.5±19.4 mg/dL respectively.

As shown in the Graph. 4, glucose tolerance was markedly improved after 7 days of exercise. Blood glucose concentration at 120th minute in OGTT before and after 7 days of exercise averaged 140.1±16.1 and 123.5±13.5 mg/dL respectively(P=0.01). The area under the glucose tolerance curve decreased 9.6% from 19,404±434 to 17,535±447 mg/dL(P<0.05) as a result of 7 days of exercise.

Among the 10 individuals with impaired glucose tolerance, 80% individuals had normal OGTTs after a week of exercise.

Prediabetes represents a dynamic and potentially reversible metabolic state characterized by impaired fasting glucose (IFG) and/or impaired glucose tolerance (IGT), both of which significantly increase the risk of progression to type 2 diabetes mellitus (T2DM). Importantly, the presence of a seemingly “healthy” metabolic profile does not fully mitigate the risk of diabetes in individuals with overweight or obesity, highlighting the complex interplay between adiposity, insulin resistance, and genetic susceptibility (8)(13). In the present study, the incidence of prediabetes based on fasting blood glucose was 27%, with a higher prevalence among women (68%) compared to men. This gender disparity may be attributed to differences in body fat distribution, hormonal influences, and lower levels of physical activity. Furthermore, the observation that IFG was more prevalent than IGT (as shown in Graph 2) aligns with existing evidence suggesting hepatic insulin resistance as an early defect in glucose dysregulation (9).

From a biochemical and physiological perspective, exercise plays a critical role in modulating glucose homeostasis through multiple interconnected mechanisms. Skeletal muscle, which accounts for the majority of postprandial glucose disposal, is a primary site where exercise exerts its effects. During moderate-intensity exercise, muscle contractions stimulate glucose uptake via insulin-independent pathways, primarily through the activation of AMP-activated protein kinase (AMPK) and calcium–calmodulin–dependent protein kinase. These signaling cascades promote the translocation of glucose transporter type 4 (GLUT4) from intracellular vesicles to the cell membrane, thereby facilitating increased glucose entry into muscle cells even in the presence of insulin resistance. This acute effect is complemented by enhanced insulin sensitivity that persists for up to 24–72(15) hours post-exercise, explaining why prolonged inactivity beyond this period may lead to deterioration in glucose tolerance (10)(14).

In addition to improving peripheral glucose uptake, regular moderate-intensity exercise induces several chronic adaptations that collectively enhance metabolic health. These include increased mitochondrial biogenesis and oxidative enzyme activity, which improve the efficiency of glucose oxidation and reduce the accumulation of lipid intermediates such as diacylglycerol and ceramides—key mediators of insulin resistance. Exercise also reduces visceral adiposity and systemic inflammation by decreasing pro-inflammatory cytokines such as TNF-α and IL-6, while increasing anti-inflammatory mediators like adiponectin. This shift in the inflammatory milieu contributes to improved insulin signaling and glucose utilization.

At the level of pancreatic β-cells, exercise has been shown to preserve function and enhance insulin secretion in response to glucose. Improved β-cell responsiveness, combined with reduced insulin demand due to enhanced peripheral sensitivity, helps delay the progression from prediabetes to overt diabetes. Furthermore, exercise favorably modulates hepatic glucose production by improving hepatic insulin sensitivity, thereby reducing excessive gluconeogenesis—a key contributor to elevated fasting glucose levels observed in IFG(16).

The findings of the present study demonstrate that even a short duration of regular moderate-intensity exercise can significantly improve glucose tolerance. This is particularly relevant in real-world settings, as moderate-intensity activities such as brisk walking are accessible, cost-effective, and sustainable across diverse populations. Notably, evidence suggests that a high volume of moderate-intensity exercise (e.g., approximately 13.8 miles per week or 30 minutes of brisk walking daily) can be as effective as intensive, multicomponent lifestyle interventions involving dietary modification and weight loss in preventing diabetes (12)(17). This reinforces the concept that consistent, achievable lifestyle changes can yield substantial metabolic benefits.

Future prospects in this field lie in the development of personalized exercise prescriptions based on genetic, metabolic, and behavioral profiles. Advances in wearable technology and continuous glucose monitoring systems may enable real-time assessment of glycemic responses to physical activity, allowing for tailored interventions in individuals with prediabetes. Additionally, further research is needed to explore the molecular signatures associated with exercise responsiveness, particularly in South Asian populations who exhibit unique metabolic characteristics. Longitudinal studies examining the sustainability of exercise-induced improvements and their impact on long-term diabetes prevention will be crucial. Integrating structured exercise programs into primary healthcare and community-based interventions could play a transformative role in curbing the rising burden of diabetes globally,

In conclusion, this study demonstrates a high prevalence of prediabetes among sedentary overweight individuals, underscoring the need for early identification and intervention in this at-risk population. The findings indicate that even a short duration of moderate-intensity exercise results in a statistically significant improvement in glucose tolerance, reflecting enhanced insulin sensitivity. Given that the beneficial effects of exercise on insulin sensitivity persist for up to 48 hours, regular and sustained physical activity is essential for maintaining optimal glycemic control(18) Moderate-intensity exercise, being simple, accessible, and sustainable, represents an effective non-pharmacological strategy for the prevention and early management of dysglycemia. Incorporating such lifestyle modifications at an early stage may play a crucial role in reducing the progression to Type 2 diabetes mellitus and its associated complications.

1. Genitsaridi I, Boyko EJ, Magliano DJ, et al. Global, regional, and national diabetes prevalence estimates for 2024 and projections for 2050: results from the International Diabetes Federation Diabetes Atlas, 11th edition. Lancet Diabetes Endocrinol. 2026;14(2):149–156.
2. International Diabetes Federation. IDF Diabetes Atlas, 11th ed. Brussels, Belgium: International Diabetes Federation; 2025. Available from: https://diabetesatlas.org
3. World Health Organization. Diabetes fact sheet. Geneva: WHO; 2024. Available from: https://www.who.int/news-room/fact-sheets/detail/diabetes
4. Duarte-Mendes P, et al. (Un)healthy lifestyles, aging, and type 2 diabetes: emerging global trends. Front Aging. 2025;1696856.
5. Prasetyo MB, et al. Relationship between physical activity and blood glucose levels in patients with type 2 diabetes mellitus. J Kesehat Dan Sains. 2025.
6. International Diabetes Federation. Diabetes facts and figures [Internet]. Brussels: International Diabetes Federation; 2021 [cited 2026 Apr 23]. Available from: https://idf.org/aboutdiabetes/what-is-diabetes/facts-figures.html
7. Misra A, Gopalan H, Jayawardena R, et al. Diabetes in developing countries. J Diabetes. 2019 Jul;11(7):522-539. doi:10.1111/1753-0407.12913.
8. Shaibi GQ, Roberts CK, Goran MI. Exercise and insulin resistance in youth. Exerc Sport Sci Rev. 2008 Jan;36(1):5-11. doi:10.1097/JES.0b013e31815e38c5.
9. Miller AD, Ruby BC, Laskin JJ, et al. Effects of high intensity / low volume and low intensity / high volume isokinetic resistance exercise on post-exercise glucose tolerance. J Strength Cond Res[Internet]. 2007 May;21(2):330-5. Available from: 10.1519/R-14363.1.
10. Bonen A, Ball-Burnett M, Russel C. Glucose tolerance is improved after low- and high-intensity exercise in middle-age men and women. Can J Appl Physiol[Internet].1998 Dec;23(6):583-93. Available from: 10.1139/h98-033.
11. Centers for Disease Control and Prevention. Diabetes Tests[Internet].USA:CDC;2021[updated 2021 August 10].Available from: https://www.cdc.gov/diabetes/basics/getting-tested.html
12. Centers for Disease Control and Prevention. Measuring physical activity intensity [Internet]. Atlanta (GA): Centers for Disease Control and Prevention; 2022 [updated 2022 Jun 3; cited 2026 Apr 23]. Available from: https://www.cdc.gov/physicalactivity/basics/measuring/index.html
13. Twig G, Afek A, Derazne E, et al. Diabetes risk among overweight and obese metabolically healthy young adults. Diabetes Care. 2014 Nov;37(11):2989-2995. doi:10.2337/dc14-0869.
14. Anjana RM, Deepa M, et al; ICMR–INDIAB Collaborative Study Group. Prevalence of diabetes and prediabetes in 15 states of India: results from the ICMR-INDIAB population-based cross-sectional study. Lancet Diabetes Endocrinol. 2017;5:585-596.
15. Colberg SR, Albright AL, Blissmer BJ, et al. Exercise and type 2 diabetes: American College of Sports Medicine and the American Diabetes Association: joint position statement. Exercise and type 2 diabetes. Med Sci Sports Exerc[Internet].2010Dec;42(12):2282-303.Available from: 10.1249/MSS.0b013e3181eeb61c.
16. Yaribeygi H, Atkin SL, Simental-Mendía LE, et al. Molecular mechanisms by which aerobic exercise induces insulin sensitivity. J Cell Physiol[Internet]. 2019 Aug;234(8):12385-12392. Available from: 10.1002/jcp.28066.
17. Slentz CA, Bateman LA, Willis LH, et al. Effects of exercise training alone vs a combined exercise and nutritional lifestyle intervention on glucose homeostasis in prediabetic individuals: a randomized controlled trial. Diabetologia[Internet]. 2016 Oct;59(10):2088-98.
18. Bird SR, Hawley JA. Update on the effects of physical activity on insulin sensitivity in humans. BMJ Open Sport Exerc Med. 2017;2(1):e000143. doi:10.1136/bmjsem-2016-000143.