Global Health Burden Shifts as Non-Communicable Diseases and Metabolic Risks Rise
New findings from the Global Burden of Disease Study 2021 (GBD 2021) reveal a significant shift in global health challenges, with non-communicable diseases (NCDs) and associated metabolic risk factors increasingly dominating the disease burden worldwide. The comprehensive analysis, published in The Lancet, highlights a troubling trend of rising disability-adjusted life-years (DALYs) attributable to conditions like high systolic blood pressure, high fasting plasma glucose, and high body-mass index (BMI), even as progress continues in reducing the burden of communicable, maternal, neonatal, and nutritional (CMNN) diseases.
The GBD 2021 study, which systematically quantified the contributions of 88 risk factors across 204 countries and territories from 1990 to 2021, used data from over 54,000 distinct sources. It found that while age-standardized DALY rates for all causes combined decreased by 14.2% globally between 2010 and 2019, this progress reversed during the first two years of the COVID-19 pandemic, with increases of 4.1% in 2020 and 7.2% in 2021. In 2021, COVID-19 became the leading cause of DALYs globally, underscoring the pandemic’s profound impact on public health.
Key Findings on Risk Factors and Disease Burden
In 2021, particulate matter air pollution emerged as the leading contributor to the global disease burden, accounting for 8.0% of total DALYs, followed closely by high systolic blood pressure (7.8%) and smoking (5.7%). Other significant risk factors included low birthweight and short gestation (5.6%) and high fasting plasma glucose (5.4%). This ranking represents a notable shift compared to previous decades.
Between 2000 and 2021, the analysis observed a significant decline in DALYs attributable to behavioral risks (a 20.7% decrease) and environmental and occupational risks (a 22.0% decrease). These reductions were largely driven by declining exposure to risks such as child and maternal malnutrition and unsafe water, sanitation, and handwashing (WaSH). For instance, age-standardized DALYs for child growth failure decreased by 71.5%, and for unsafe water sources by 66.3%.
However, DALYs attributable to metabolic risks increased by a substantial 49.4% during the same period. This rise is primarily linked to aging populations and changing lifestyles globally. Specifically, age-standardized global DALY rates attributable to high BMI rose by 15.7% and high fasting plasma glucose by 7.9% from 2000 to 2021, with exposure to these risks increasing annually.
The study also introduced a new methodology called the burden of proof risk function (BPRF) to assess the strength of evidence for risk-outcome associations. For most leading risk factors contributing to the highest disease burden, such as particulate matter pollution, high systolic blood pressure, smoking, and high fasting plasma glucose, the supporting evidence for their health effects was found to be strong and consistent. However, for other risk factors like low temperature and several dietary risks, the evidence was less robust, indicating a need for further research.
Age, Sex, and Geographic Disparities
The impact of risk factors varied considerably across different demographic groups. For children aged 0-4 years, leading risks included low birthweight and short gestation, child growth failure, and unsafe WaSH. For older age groups, metabolic risks such as high systolic blood pressure, high BMI, high fasting plasma glucose, and high LDL cholesterol had a greater impact. Behavioral risk factors, including high alcohol use and smoking, disproportionately affected individuals aged 15-49 years.
Geographically, age-standardized DALY rates for child and maternal malnutrition were highest in sub-Saharan Africa, South Asia, and parts of North Africa and the Middle East. Air pollution also showed high rates in these regions. In contrast, locations with higher Socio-demographic Index (SDI) experienced slower declines in behavioral risk-attributable burden but higher rates of decline in metabolic risk-attributable burden, particularly for high systolic blood pressure and high LDL cholesterol.
Long-Term Health Projections to 2050
Looking ahead, a separate forecasting analysis also published in The Lancet predicts continued increases in global life expectancy but at a slower pace than in the decades preceding the COVID-19 pandemic. Global life expectancy is projected to reach 78.2 years by 2050. However, the total number of DALYs is expected to increase in every super-region, largely due to population aging and growth. The burden of disease will continue its shift from CMNNs to NCDs, with NCDs accounting for 77.6% of global DALYs by 2050.
Alternative scenarios exploring the impact of eliminating certain risk factors by 2050 demonstrated significant potential for health gains. The “Improved Behavioral and Metabolic Risks” scenario showed the strongest impact, potentially leading to a 13.3% decrease in global DALYs compared to the reference scenario. The combined elimination of risks across environmental, childhood nutrition, vaccination, behavioral, and metabolic categories could result in 15.4% fewer DALYs globally. This indicates that interventions targeting metabolic risks and smoking have the greatest potential for reducing overall disease burden.
Public Health Implications
These findings underscore the complex and evolving nature of global health challenges. While notable progress has been made against CMNN diseases, the escalating burden of NCDs and metabolic risks demands urgent attention. Sustained investment in evidence-based interventions and policies is crucial to maintain progress in maternal and child health and address new threats. The Global Burden of Disease Study 2023, scheduled for release in October 2025, will provide further updated insights into these trends, including a deeper look into 375 diseases and injuries and the risk-attributable burden of 88 risk factors from 1990-2023, according to pre-published abstracts.
Policymakers must consider location-specific and population-specific strategies. For high-SDI areas, emphasizing policies to reduce metabolic risk exposure (e.g., through promoting healthier diets, physical activity, and access to treatments like GLP-1 receptor agonists) and tobacco cessation is paramount. In low-SDI settings, continuing efforts to combat child malnutrition, improve WaSH, and enhance vaccination coverage remain critical, particularly in regions like sub-Saharan Africa where population growth will continue to strain health systems. Read more on Globally Pulse Health.
The analysis also cautions against potential setbacks. Major cuts to global health development assistance could reverse gains, especially in low-income countries that bear a disproportionate disease burden. Addressing both the long-standing health disparities and the rapidly growing NCD epidemic requires a decisive, coordinated global response that prioritizes equitable healthcare access, strong health systems, and comprehensive prevention strategies.
