Published Aug 31, 2026 | 7:00 AM ⚊ Updated Aug 31, 2026 | 7:00 AM
Diabetes prevalence in India has risen steadily, from about 9% (age-adjusted) in 2011 to projections of 10.8% by 2045.(Representational image/iStock)
Synopsis: India’s diabetes burden may face an emerging climate-related threat. A new review examines how rising heat, air pollution and extreme weather can disrupt glucose regulation, insulin signalling and metabolic health. With 101 million Indians living with diabetes, researchers call for stronger evidence and climate-informed prevention and care strategies.
India’s diabetes epidemic may have another factor to contend with: a changing climate. A new review traces how rising heat, air pollution and extreme weather can reach beyond the environment, disrupting the body’s systems that regulate blood sugar and potentially increasing the risk of diabetes and its complications.
The review, published in Current Diabetes Reports, estimates that 101 million people in India were living with diabetes in 2023. Adult prevalence is roughly 11%, up sharply from 26 million in 1990. The authors examine how climate-related exposures could compound established risk factors such as diet, obesity and physical inactivity.
The review, titled Climate Change and Diabetes Outcomes: Evidence from Climate-Vulnerable Regions, was written by researchers from Harvard T.H. Chan School of Public Health, Madras Diabetes Research Foundation, Dr Mohan’s Diabetes Specialities Centre in Chennai, Kuwait University and Dasman Diabetes Institute. India and Kuwait serve as the two case studies.
“Traditional risk factors and risk modifiers for metabolic diseases have been extensively studied for many decades now,” the authors write. “These include genetics, ageing, obesity, physical inactivity, diet, smoking, socioeconomic status, access to healthcare, and many others. Together, they explain much of the global burden of type 2 diabetes. However, emerging climate-related exposures are now recognized for their impacts on a wide range of human health consequences, including the burden of chronic diseases.”
India combines a large and growing diabetes burden with increasing exposure to heat and air pollution, the review notes.
Air pollution levels in India are among the highest in the world, with virtually the entire 1.4 billion population exposed to unhealthy levels of fine particulate matter year-round, according to the review. Major Indian cities frequently rank among the world’s most polluted, while rural populations are also exposed to pollution from biomass burning and dust.
India has also experienced more frequent and intense heat waves in recent years. Summer temperatures in many parts of the country routinely exceed 40°C. At the same time, only about 8-10% of Indian households own an air conditioner.
The authors note that rising heat and pollution may contribute to increased metabolic stress, adding to traditional risk factors such as diet and obesity. Climate variability can also affect crop yields, food prices and dietary diversity.
The concern is not that heat and pollution operate independently. The review describes climate-related exposures as converging pressures that can affect metabolic health and, among people already living with diabetes, make disease management more difficult.
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The clearest evidence in the review for climate-related exposure and the development of new diabetes comes from air pollution.
A prospective cohort study from Chennai and Delhi found that every 10 microgram-per-cubic-metre increase in PM2.5 exposure was associated with higher fasting plasma glucose and HbA1c levels and an approximately 22% increased risk of type 2 diabetes. The researchers also reported an association between PM2.5 exposure and dyslipidaemia.
The review describes a biological pathway that could explain this association.
Fine particulate matter can penetrate deep into the lungs and enter the bloodstream. Once in the body, PM2.5 can induce oxidative stress, systemic inflammation, endothelial dysfunction and inflammation in adipose tissue. These processes can impair insulin signalling and promote insulin resistance.
The review also points to specific inflammatory pathways. Experimental studies have shown that PM2.5 can activate pathways such as NF-κB and toll-like receptors, contributing to impaired insulin signalling in muscle and liver tissue.
Nitrogen dioxide, a marker of traffic-related air pollution, has also been associated with metabolic dysfunction. Meta-analyses and systematic reviews cited in the review link long-term NO₂ exposure with increased type 2 diabetes risk and impaired glycaemic regulation.
The evidence is not limited to India. A multi-country study covering more than 3.6 million diabetes hospitalisations across seven countries found that every 10 microgram-per-cubic-metre increase in wildfire-specific PM2.5 exposure over the same day and preceding three days was associated with a 2-3% increase in type 2 diabetes hospitalisation risk. Wildfire-specific PM2.5 accounted for nearly 39% of total PM2.5-attributable diabetes hospitalisations in that study.
Dust exposure has also been linked to diabetes-related hospitalisation. One study found that for every 10 microgram-per-cubic-metre increase in dust-specific PM2.5, diabetes hospitalisation risk increased by 3%.
The physiological pathway looks different with heat.
People with diabetes can have impaired thermoregulation, particularly those with autonomic neuropathy. High temperatures increase the body’s demand for heat dissipation. Under hot and humid conditions, reduced evaporative cooling can increase cardiovascular strain, while heat exposure can lead to rapid dehydration, plasma-volume depletion and electrolyte imbalance.
Severe dehydration can exacerbate hyperglycaemia and worsen hyperosmolar hyperglycaemic state. Heat also activates the hypothalamic-pituitary-adrenal axis and sympathetic nervous system, increasing the release of counter-regulatory hormones including cortisol, adrenaline and glucagon.
These hormones stimulate hepatic glucose production, worsen insulin resistance and promote lipolysis and ketogenesis, increasing the risk of diabetic ketoacidosis.
Heat can also affect vascular health. Dehydration-induced haemoconcentration combined with increased peripheral blood-flow demands can impair tissue perfusion and increase thrombosis risk, particularly among people with underlying peripheral vascular disease.
Heat can even affect insulin administration. Increased cutaneous blood flow can alter insulin absorption, while high temperatures can reduce insulin stability during storage. This can result in unpredictable glycaemic fluctuations.
The vulnerability can be greater among people with diabetes who also have cardiovascular disease or take medications that can affect thermoregulation and dehydration risk.
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Climate-related risk extends beyond what happens directly inside the body.
Floods and storms can damage hospitals and clinics, forcing closures and preventing people from attending appointments, obtaining insulin refills or receiving routine monitoring. The review notes that such gaps can continue for months after an extreme weather event.
Disasters can also interrupt laboratory services, damage medical records and affect water supplies and primary-care functions.
For people living with diabetes, these disruptions can turn a climate event into a prolonged medical problem. Missed appointments, interrupted medication supplies and inadequate monitoring can contribute to gaps in diabetes management.
The review’s graphical model brings these pathways together. Heat can drive dehydration and alter insulin stability. Air pollution can contribute to oxidative stress, inflammation and insulin resistance. Extreme weather can disrupt medication supplies, monitoring and healthcare access. Together, these pressures can contribute to glycaemic instability and acute metabolic complications.
The authors caution that the evidence linking climate-related exposures specifically to diabetes in India remains incomplete.
A multi-city time-series analysis of approximately 3.6 million deaths across 10 Indian cities between 2008 and 2019 found strong synergistic effects between heat and PM2.5. Pollution-related mortality increased as temperatures rose, with the analysis finding particularly high risks during days when extreme heat coincided with high PM2.5 levels.
A separate national analysis found that rising summer mean temperatures in India were associated with a 146% increase in the probability of large heat-related mortality events involving more than 100 deaths.
However, these findings primarily concern mortality rather than diabetes incidence.
The authors therefore stress the need for longitudinal studies that can distinguish the effects of repeated and combined exposure to heat and air pollution on diabetes development, disease progression, glycaemic management and complications.
“Together, while these findings suggest that climate-related factors may increase diabetes risk, there remains an urgent need for longitudinal studies in India that quantify the combined and non-linear effects of heat and air pollution on diabetes incidence, management, and complications across rural and urban Indian populations,” the authors write.
They call for research that measures exposure both indoors and outdoors and accounts for housing quality, ventilation, access to cooling and occupational exposure. They also recommend wearable sensors and high-resolution models to better capture individual exposure.
The authors further call for laboratory and mechanistic studies examining how heat, particulate matter and dehydration interact with insulin signalling, inflammation, endothelial function, renal physiology and hormonal regulation.
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The implications extend beyond research.
The review calls for evidence that can help policymakers identify heat and pollution thresholds relevant to people with diabetes, develop early-warning systems, improve urban and housing design and maintain continuity of diabetes care during extreme weather events.
“Decision makers at the city scale, for example, need evidence-based input from both the scientific community as well as from other cities who have implemented policies and practices that can be objectively evaluated,” the authors note.
The review stops short of establishing climate change as a direct cause of diabetes. Instead, it presents a growing body of evidence showing that climate-related exposures can affect physiological pathways involved in glucose regulation and insulin sensitivity, while also worsening outcomes among people already living with diabetes.
For India, that distinction matters. The country is already home to an estimated 101 million people with diabetes. As heat and pollution intensify, the emerging question is whether environmental stress will add another layer of metabolic pressure to an epidemic that is already placing a substantial burden on the health system.
The review concludes that diabetes should increasingly be treated as a climate-sensitive condition.
“Diabetes is ought to be seen as a climate-sensitive condition, where more prevention strategies and clinical guidance is needed to protect people with diabetes, globally,” the authors write.
(Edited by Fayisa CA)
