What are the different types of diabetes and their prevalence rates?

Types of Diabetes Mellitus and Their Prevalence

There are four main types of diabetes mellitus recognized in the scientific world: Type 1 diabetes, Type 2 diabetes, Gestational diabetes, and Specific types of diabetes due to other causes. 1

Main Types of Diabetes and Their Prevalence

Type 1 Diabetes

• Results from autoimmune β-cell destruction, usually leading to absolute insulin deficiency 1
• Accounts for approximately 5-10% of all diabetes cases 1
• In the United States, about 0.55% of adults (approximately 1.3 million people) have diagnosed type 1 diabetes, representing 5.8% of all diagnosed diabetes cases 2
• Often presents with classic symptoms of polyuria/polydipsia, and approximately one-third of children present with diabetic ketoacidosis 1
• Can be further classified into immune-mediated diabetes and idiopathic diabetes 1

Type 2 Diabetes

• Caused by progressive loss of β-cell insulin secretion frequently on the background of insulin resistance 1
• Most common form, accounting for 90-95% of all diabetes cases 1
• In the United States, about 8.6% of adults (approximately 21.0 million people) have diagnosed type 2 diabetes, representing 90.9% of all diagnosed diabetes cases 2
• Prevalence increases with age, obesity, and lack of physical activity 1
• Higher prevalence among certain ethnic groups: Native Americans and Alaskan Natives (15.1%), non-Hispanic blacks (12.7%), and Hispanics (12.1%) compared with Asians (8.0%) and non-Hispanic whites (7.4%) 1

Gestational Diabetes Mellitus (GDM)

• Diabetes diagnosed in the second or third trimester of pregnancy that was not clearly overt diabetes prior to gestation 1
• Prevalence varies widely based on population risk factors, ranging from less than 2% in low-risk populations (such as Sweden) to as high as 17% in high-risk groups (such as Indian women in Australia) 3
• Six out of eight studies reporting on trends show an increase in GDM prevalence across most racial/ethnic groups 3

Specific Types of Diabetes Due to Other Causes

• Includes monogenic diabetes syndromes (such as neonatal diabetes and maturity-onset diabetes of the young [MODY]) 1
• Diseases of the exocrine pancreas (such as cystic fibrosis and pancreatitis) 1
• Drug or chemical-induced diabetes (such as with glucocorticoid use, in the treatment of HIV/AIDS, or after organ transplantation) 1
• These types account for approximately 3.3% of all diagnosed diabetes cases 2

Additional Classifications

Hybrid Forms of Diabetes

• Includes slowly evolving immune-mediated diabetes and ketosis-prone type 2 diabetes 4
• Latent autoimmune diabetes in adults (LADA) - phenotypically similar to type 2 diabetes but patients have autoantibodies 1

Prediabetes

• Now referred to as "categories of increased risk for diabetes" 1
• Includes impaired fasting glucose, impaired glucose tolerance, or an A1C level of 5.7-6.4% 1
• Affects approximately 33.9% of U.S. adults (84.1 million people) 1
• Nearly half (48.3%) of adults 65 or older have prediabetes 1

Global Burden and Future Projections

• In 2021, there were 529 million people living with diabetes worldwide (6.1% age-standardized prevalence) 5
• Type 2 diabetes accounted for 96.0% of diabetes cases and 95.4% of diabetes disability-adjusted life years (DALYs) worldwide in 2021 5
• Highest regional prevalence rates were observed in Oceania (12.3%) and North Africa/Middle East (9.3%) 5
• By 2050, more than 1.31 billion people are projected to have diabetes globally 5
• By 2050,89 countries (43.6% of 204 countries and territories) will have an age-standardized diabetes prevalence rate greater than 10% 5

Risk Factors and Demographics

• High body-mass index (BMI) is responsible for 52.2% of global type 2 diabetes DALYs 5
• The contribution of high BMI to type 2 diabetes DALYs rose by 24.3% worldwide between 1990 and 2021 5
• Age-adjusted incidence of diabetes is two times higher for people with less than a high school education compared to those with more than a high school education 1
• Diabetes prevalence increases with age: 4% in individuals 18-44 years old, 17% in those 45-64 years old, and 25% in those 65 and older 1

Clinical Implications

• Understanding the prevalence of diagnosed diabetes by type is crucial for monitoring trends, planning public health responses, and prioritizing health services 2
• Type 2 diabetes is largely preventable and potentially reversible if identified and managed early 5
• All evidence indicates that diabetes prevalence is increasing worldwide, primarily due to rising obesity rates 5
• Preventing and controlling type 2 diabetes remains an ongoing challenge requiring targeted strategies to address risk factors 5