Epidemiology is the scientific study of the distribution and determinants of health-related states, including chronic conditions like diabetes. By examining how, when, and where diabetes occurs, researchers and public health officials can identify patterns, understand risk factors, and measure the disease’s overall burden. This field provides the data that illustrates the condition’s impact on communities worldwide. It helps to quantify the scope of the problem and track its progression, providing a foundation for developing prevention and management strategies.
Global Prevalence and Incidence
The global scale of diabetes is significant and growing. Prevalence refers to the total number of people living with a disease at a specific point in time, while incidence measures new cases over a defined period. According to the International Diabetes Federation (IDF), approximately 589 million adults between 20 and 79 live with diabetes, which translates to about one in nine adults globally.
A high number of these cases are undiagnosed. The IDF estimates that 252 million people, or 43% of adults with diabetes, are unaware they have the condition. This lack of diagnosis prevents timely management and increases the risk of complications. The health expenditure related to diabetes was estimated at over one trillion U.S. dollars in 2024, reflecting the resources required to manage the condition.
Distribution by Diabetes Type
The global diabetes numbers are primarily composed of three main types. Type 2 diabetes is the most common form, accounting for over 90% of all diabetes cases in adults. This condition is characterized by insulin resistance, where the body’s cells do not respond effectively to insulin, often combined with a relative deficiency in insulin production. Its onset typically occurs in adulthood and is strongly associated with lifestyle and metabolic factors.
Type 1 diabetes makes up a smaller portion of the total cases, estimated at around 5-10%. It is an autoimmune condition where the body’s immune system mistakenly attacks and destroys the insulin-producing beta cells in the pancreas. Consequently, the body produces little to no insulin. While it can be diagnosed at any age, Type 1 diabetes most frequently appears in children and adolescents. In 2021, reports indicated that over 1.2 million children and adolescents under the age of 19 were living with Type 1 diabetes.
Gestational diabetes mellitus (GDM) is a type of diabetes that develops during pregnancy in women without a previous diagnosis of diabetes, affecting approximately one in six pregnancies. GDM typically resolves after delivery, but it increases the mother’s risk of developing Type 2 diabetes later in life. It also poses risks for the infant, including a higher likelihood of obesity and developing Type 2 diabetes in the future. The prevalence of GDM has been rising globally, paralleling the increase in obesity rates among women of childbearing age.
Key Risk Factors and Demographics
The risk of developing diabetes is influenced by a combination of non-modifiable and modifiable factors. Non-modifiable factors are those that cannot be changed, such as age, genetic predisposition, and ethnicity. The prevalence of Type 2 diabetes increases significantly with age, and data shows the highest prevalence, 24.0%, is observed in adults aged 75-79 years. A family history of diabetes also elevates an individual’s risk.
Certain racial and ethnic groups exhibit a higher predisposition to developing Type 2 diabetes. For instance, populations of South Asian, African, and Hispanic descent experience higher rates of the condition compared to those of European ancestry. These disparities are the result of a complex interplay between genetic susceptibilities and environmental influences.
Modifiable risk factors are major drivers of the Type 2 diabetes epidemic. Overweight and obesity, particularly the accumulation of visceral fat around the abdomen, are strongly linked to the development of insulin resistance. Physical inactivity and unhealthy dietary patterns, characterized by high intake of calories, processed foods, and sugary beverages, also contribute significantly to this risk.
Geographic and Socioeconomic Patterns
The burden of diabetes is not distributed equally across the globe. A significant shift has occurred in recent decades, with the condition no longer being primarily associated with affluent nations. Today, over four in five adults with diabetes live in low- and middle-income countries (LMICs), which are experiencing the most rapid increase in prevalence.
The prevalence rates vary considerably by region. For instance, the Middle East and North Africa region has the highest comparative prevalence of diabetes, while the African region currently has the lowest. Within countries, urban areas typically show higher rates of diabetes compared to rural areas, with urban prevalence at 12.1% versus 8.3% in rural settings in 2021. This disparity is often linked to greater access to processed foods and more sedentary lifestyles in cities.
Socioeconomic factors within countries also play a part in diabetes risk and outcomes. In high-income countries, diabetes tends to be more common among populations with lower income and education levels. Conversely, in some low- and middle-income countries, the risk can be higher among more educated and wealthier individuals, a pattern that may shift as economic development continues.
Trends and Projections
The epidemiology of diabetes has been characterized by a dramatic upward trend. In 1980, an estimated 108 million adults were living with diabetes globally. This sharp increase reflects the global rise in associated risk factors, particularly obesity and physical inactivity, alongside population growth and aging.
Looking ahead, projections from the International Diabetes Federation indicate that this trend is expected to continue. The number of adults living with diabetes is forecasted to reach 783 million by the year 2045. This represents a 46% increase, a rate that far outpaces projected global population growth over the same period.
The most significant growth in the number of people with diabetes is anticipated to occur in regions currently classified as low- and middle-income. These areas are projected to account for the vast majority of the increase in cases, further straining healthcare systems that are often already under-resourced. These projections highlight the ongoing and escalating nature of the diabetes epidemic.