Diabetes is a chronic condition that affects how your body processes blood sugar (glucose). When you have diabetes, your body either doesn’t make enough insulin or can’t use insulin properly. This leads to high blood sugar levels, which can cause serious health problems over time. Diabetes affects about 1 in 10 adults worldwide (1).

Table of Contents

List of Diabetes Types

Understanding the different types of diabetes helps with proper diagnosis and treatment. Each type has unique characteristics and treatment approaches.

Type 1 Diabetes

Type 1 diabetes is an autoimmune condition where your immune system attacks and destroys the cells in your pancreas that make insulin. This type usually develops in children and young adults, though it can occur at any age. About 600,900 children under 15 years old have type 1 diabetes worldwide (2).

People with type 1 diabetes need insulin therapy for life. The condition can be diagnosed using autoantibody tests, which detect antibodies that attack insulin-producing cells. A large meta-analysis including 71,482 participants found that islet autoantibodies can effectively predict progression to type 1 diabetes (3).

Common symptoms include excessive thirst, frequent urination, and unexplained weight loss. In children with type 1 diabetes, as many as 55% present with diabetic ketoacidosis at diagnosis (4).

Read more about Type 1 Diabetes

Type 2 Diabetes

Type 2 diabetes is the most common form of diabetes, making up 90-95% of all diabetes cases (5). In this type, your body becomes resistant to insulin or doesn’t produce enough insulin. It typically develops in adults but is increasingly being diagnosed in children and teenagers.

The global prevalence of diabetes (mostly type 2) is estimated at 9.3% of adults, affecting 463 million people worldwide. This number is expected to rise to 700 million by 2045 (6).

Treatment typically starts with lifestyle changes and may include medications. Metformin is often the first medication prescribed. For people with kidney disease or heart disease, certain newer medications called SGLT2 inhibitors or GLP-1 receptor agonists are recommended (7).

Read more about Type 2 Diabetes

Gestational Diabetes Mellitus (GDM)

Gestational diabetes is a type of diabetes that develops during pregnancy. It affects women who have never had diabetes before but develop high blood sugar levels during pregnancy. In Europe, about 11% of pregnant women develop gestational diabetes (8).

Women who are older, overweight, or obese have a higher risk. The risk is 2.14 times higher in women aged 30 or older compared to younger women (8).

After pregnancy, women with gestational diabetes have a higher risk of developing type 2 diabetes. Studies show they are more than 6 times more likely to develop type 2 diabetes compared to women who didn’t have gestational diabetes (9). A comprehensive review from India also confirmed that women with gestational diabetes are at significantly increased risk of developing type 2 diabetes (10).

Read more about Gestational Diabetes

Latent Autoimmune Diabetes in Adults (LADA)

LADA, sometimes called type 1.5 diabetes, is a form of type 1 diabetes that develops slowly in adults. Like type 1 diabetes, it’s caused by the immune system attacking insulin-producing cells. However, the process happens more slowly than in typical type 1 diabetes.

A systematic review and meta-analysis of 51,725 individuals found that the worldwide prevalence of LADA is 8.9% among adults with diabetes (11).

LADA can be distinguished from type 2 diabetes by testing for diabetes autoantibodies. People with LADA eventually need insulin treatment, though they may not need it right away at the time of diagnosis. Unlike typical type 2 diabetes, certain oral medications (like sulfonylureas) may cause earlier insulin dependence in people with LADA (12).

Read more about Latent Autoimmune Diabetes in Adults

Prediabetes

Prediabetes means your blood sugar levels are higher than normal but not high enough to be diagnosed as diabetes. In the United States, about 1 in 3 adults has prediabetes. However, most people don’t know they have it. Only about 11% of people with prediabetes are aware of their condition (13).

Without lifestyle changes, about 11% of people with prediabetes will develop type 2 diabetes each year. The good news is that lifestyle changes can prevent or delay this progression. Weight loss, healthy eating, and regular physical activity can significantly reduce the risk (13).

Read more about Prediabetes

Common Symptoms of Diabetes

Recognizing the symptoms of diabetes early can lead to timely diagnosis and treatment. While symptoms can vary by type, many are similar across different forms of diabetes.

General Diabetes Symptoms

The most common symptoms occur because high blood sugar affects your whole body:

  • Excessive thirst and dry mouth
  • Frequent urination, especially at night
  • Extreme tiredness and fatigue
  • Blurred vision
  • Unexplained weight loss
  • Slow-healing wounds or frequent infections
  • Numbness or tingling in hands or feet

Type 1 Diabetes Symptoms

Type 1 diabetes symptoms often develop quickly over weeks or months. In children, increased urination may cause bedwetting after toilet training. About 55% of children with type 1 diabetes present with diabetic ketoacidosis at diagnosis, which is a medical emergency (4).

Type 2 Diabetes Symptoms

Type 2 diabetes symptoms develop more slowly and may be so mild that you don’t notice them. Many people have no symptoms and only discover they have diabetes through routine blood tests. When symptoms do occur, they’re similar to general diabetes symptoms but may also include:

  • Dark patches of skin (acanthosis nigricans) (14)
  • Skin tags
  • Frequent yeast infections

Gestational Diabetes Symptoms

Most women with gestational diabetes have no symptoms. The condition is usually discovered through routine pregnancy screening tests. When symptoms do occur, they may include excessive thirst and frequent urination.

Diabetes by Demographics

Diabetes affects people differently based on age, location, and other factors.

Diabetes in Children and Adolescents

Type 1 diabetes is the most common form in children, though type 2 diabetes is becoming more common in young people, a change that may result from the rise in obesity. Worldwide, there are about 98,200 new cases of type 1 diabetes in children under 15 each year. The total number of children and adolescents living with type 1 diabetes continues to increase (2).

Diabetes in Adults

Most adults with diabetes have type 2 diabetes. The risk increases with age, especially after age 45. Urban areas have higher rates of diabetes (10.8%) compared to rural areas (7.2%). High-income countries also have higher rates (10.4%) than low-income countries (4.0%) (6).

Geographic Differences

Diabetes rates vary significantly around the world. About half of all people with diabetes don’t know they have it. This is especially common in areas with limited access to healthcare (6).

In the United States, diabetes incidence trends from 2008-2021 show demographic variations in disease burden (15).

Risk Factors for Diabetes

Understanding your risk factors helps you know if you should be screened for diabetes and what preventive steps you can take.

Type 1 Diabetes Risk Factors

Type 1 diabetes risk factors are mostly genetic and cannot be changed:

  • Family history (having a parent or sibling with type 1 diabetes)
  • Age (most common in children and teenagers, but can occur at any age)
  • Genetic markers associated with the disease
  • Geography (more common in certain regions)

Type 2 Diabetes Risk Factors

Type 2 diabetes has many modifiable and non-modifiable risk factors.

Non-Modifiable Risk Factors

  • Older age (risk increases with age) (16)
  • Family history of type 2 diabetes
  • Race and ethnicity (higher risk in certain populations) (17)
  • History of gestational diabetes
  • Polycystic ovary syndrome (PCOS) (18)

Modifiable Risk Factors

  • Being overweight or obese (19)
  • Physical inactivity
  • High blood pressure
  • Abnormal cholesterol levels
  • Smoking

Type 2 diabetes is linked to metabolic disorders. A meta-analysis showed that depression is associated with insulin resistance, with those having depression showing increased insulin resistance markers (20).

Gestational Diabetes Risk Factors

Risk factors for gestational diabetes include:

  • Being overweight before pregnancy
  • Age over 25
  • Previous gestational diabetes
  • Family history of type 2 diabetes
  • Previous delivery of a baby weighing more than 9 pounds
  • PCOS
  • Multiple pregnancy (twins, triplets)

Diabetes Complications

When blood sugar levels stay high over time, diabetes can cause serious complications affecting multiple body systems. These complications can be acute (sudden and severe) or chronic (developing over time).

Acute Complications

Acute complications require immediate medical attention and can be life-threatening.

Diabetic Ketoacidosis (DKA)

DKA mainly affects people with type 1 diabetes when the body doesn’t have enough insulin. Without insulin, the body breaks down fat for energy, producing ketones that make the blood acidic. Symptoms may include labored breathing, vomiting, and confusion. A systematic review found DKA rates at diagnosis vary widely, from 14.7% to 79.8% across different countries (4).

Hyperglycemic Hyperosmolar State (HHS)

HHS typically occurs in type 2 diabetes when blood sugar levels become extremely high (over 600 mg/dL), leading to severe dehydration. It’s less common than DKA but has higher mortality rates (21).

Severe Low Blood Sugar (Hypoglycemia)

This occurs when blood sugar drops too low, usually in people taking insulin or certain diabetes medications. Symptoms include confusion, shaking, sweating, and in severe cases, seizures or loss of consciousness.

Long-Term Complications

Chronic high blood sugar damages blood vessels and nerves throughout the body, leading to various complications.

Diabetic Neuropathy

Diabetic neuropathy is nerve damage caused by diabetes. It’s one of the most common complications, affecting up to half of all people with diabetes over time. A systematic review and meta-analysis of 229 studies found that pharmacotherapy can help manage neuropathic pain, with anticonvulsants and antidepressants showing effectiveness (22).

A systematic review found that peripheral neuropathy prevalence in prediabetes affects a significant portion of patients, highlighting the importance of early intervention (23).

Diabetic Foot Problems

Foot problems are common in people with diabetes. A meta-analysis of 18 studies found that global mortality of diabetic foot ulcers is significant, emphasizing the need for prevention (24).

In sub-Saharan Africa, the prevalence of diabetic foot ulcers is about 13%. Risk factors include living in rural areas, having diabetes for more than 10 years, and poor self-care practices (25).

Diabetic Eye Disease (Retinopathy)

Diabetes can damage the blood vessels in the retina, potentially leading to vision loss and blindness. High blood sugar levels can also cause other eye problems, including cataracts and glaucoma. Type 2 diabetes is associated with increased risk of various eye complications (26).

Diabetic Kidney Disease

Diabetes can damage the kidneys over time, leading to diabetic kidney disease. This is one of the leading causes of kidney failure. Several genes have been identified that may increase the risk of kidney problems in people with diabetes (27).

Other Diabetes Complications

Diabetes can affect many other parts of your body:

  • Cardiovascular complications: People with diabetes have higher risk of heart disease, heart attack, and stroke due to damage to blood vessels.
  • Skin conditions: Diabetes increases the risk of bacterial and fungal skin infections, as well as other skin problems. A meta-analysis found that Candida infections in diabetes patients show an odds ratio of 3.16 (3).
  • Hearing problems: Diabetes can damage the small blood vessels and nerves in the inner ear, leading to hearing loss.
  • Dental and gum disease: High blood sugar increases the risk of gum infections and tooth loss.
  • Sexual dysfunction: Nerve and blood vessel damage can cause erectile dysfunction in men and vaginal dryness in women.
  • Gastroparesis: Nerve damage can affect stomach emptying, causing nausea, vomiting, and bloating.
  • Mental health: People with diabetes are two to three times more likely to experience depression than those without diabetes. Managing a chronic condition can also lead to diabetes distress and anxiety.

Pregnancy Complications

Gestational diabetes can cause complications for both mother and baby.

For the baby

  • Higher birth weight (over 9 pounds)
  • Premature birth
  • Low blood sugar after birth
  • Increased risk of type 2 diabetes later in life
  • Breathing problems
  • Jaundice

For the mother

  • High blood pressure and preeclampsia
  • Increased risk of Cesarean delivery
  • Higher risk of gestational diabetes in future pregnancies
  • Increased risk of type 2 diabetes later in life

Women with previous gestational diabetes have more than 6 times higher risk of developing type 2 diabetes compared to women without gestational diabetes (9).

Causes of Diabetes

Different types of diabetes have different causes, but all types involve problems with insulin production or effectiveness.

Type 1 Diabetes Causes

Type 1 diabetes is caused by an autoimmune reaction where the body’s immune system attacks the insulin-producing cells in the pancreas. The exact trigger is unknown, but genetic factors and possibly environmental factors (like viruses) may play a role. A population-based study of 4,993 children found that those with a family history of type 2 diabetes tend to be older at type 1 diabetes diagnosis (28).

Type 2 Diabetes Causes

Type 2 diabetes develops when the body becomes resistant to insulin or doesn’t produce enough insulin. Risk factors include:

  • Being overweight or obese
  • Physical inactivity
  • Family history of diabetes
  • Age (risk increases after 45)
  • Certain ethnic backgrounds
  • History of gestational diabetes

Other Contributing Factors

People with type 1 diabetes often have other autoimmune conditions. A systematic review and meta-analysis of 180 articles involving 293,889 patients found that autoimmune diseases are significantly more prevalent in type 1 diabetes patients (29).

How Insulin Resistance Develops

In type 2 diabetes, insulin resistance develops gradually through a cycle:

  1. Your body needs more insulin to process the glucose you eat
  2. The pancreas tries to make extra insulin to keep up
  3. Over time, the pancreas can’t produce enough insulin
  4. Blood sugar levels start to rise
  5. High blood sugar causes further damage to insulin-producing cells

This process is influenced by genetics, excess weight, physical inactivity, and other factors. Endoplasmic reticulum (ER) stress plays an important role in the development of diabetes. A systematic review and meta-analysis found that ER stress biomarkers are significantly associated with type 2 diabetes and its complications (30). The good news is that lifestyle changes can help mitigate this cycle and improve insulin sensitivity.

Diabetes Diagnosis

Several blood tests can diagnose diabetes and prediabetes. Your doctor will choose the most appropriate test based on your symptoms and risk factors.

Common Diagnostic Tests

Fasting Blood Glucose Test

This test measures your blood sugar after not eating for at least 8 hours. It’s often done first thing in the morning. A result of 126 mg/dL or higher on two separate tests indicates diabetes (31).

Random Blood Glucose Test

This test can be done at any time, regardless of when you last ate. A blood sugar level of 200 mg/dL or higher, along with symptoms of diabetes, suggests a diabetes diagnosis.

Hemoglobin A1C Test

The A1C test shows your average blood sugar level over the past 2-3 months. An A1C of 6.5% or higher on two separate tests indicates diabetes. For prediabetes, the range is 5.7% to 6.4% (32).

Oral Glucose Tolerance Test (OGTT)

This test measures your blood sugar before and 2 hours after drinking a sweet liquid. It’s commonly used to diagnose gestational diabetes. For pregnant women, different values are used to diagnose gestational diabetes.

Special Testing for Type 1 Diabetes and LADA

When type 1 diabetes or LADA is suspected, additional tests for autoantibodies can confirm the diagnosis. These antibodies attack insulin-producing cells and include tests for GADA, IA-2A, IAA, and ZnT8A (33).

General Treatment Approaches

Treatment for diabetes depends on the type and individual needs, but all approaches aim to keep blood sugar levels in a healthy range.

Type 1 Diabetes Treatment

People with type 1 diabetes require insulin therapy for life since their bodies don’t produce insulin. Treatment includes:

  • Multiple daily insulin injections or insulin pump therapy
  • Regular blood sugar monitoring
  • Carbohydrate counting
  • Regular physical activity
  • Healthy eating

Research continues on new approaches. A systematic review and meta-analysis on disease-modifying immunotherapies in type 1 diabetes shows promise for future treatments (34).

Type 2 Diabetes Treatment

Type 2 diabetes treatment often starts with lifestyle changes. Medications may be used if lifestyle modifications don’t yield sufficient improvement in blood sugar control.

First-Line Treatment: Metformin is usually the first medication prescribed. It helps lower blood sugar and may prevent some diabetes-associated complications. Studies show metformin is particularly beneficial for overweight patients (35). A landmark systematic review and meta-analysis found that short-term intensive insulin therapy can be effective for newly diagnosed type 2 diabetes (36). More research is necessary recommend this approach.

Additional Medications: If metformin isn’t enough, other medications may be added. For people with heart or kidney disease, SGLT2 inhibitors or GLP-1 receptor agonists are recommended. These newer medications have shown benefits beyond blood sugar control (37).

Lifestyle Management

Lifestyle changes are important for all types of diabetes:

  • Healthy eating with focus on whole grains, vegetables, and lean proteins
  • Regular physical activity (at least 150 minutes per week) (38)
  • Weight management
  • Stress management
  • Not smoking
  • Regular medical check-ups

Prevention Strategies

While type 1 diabetes cannot currently be prevented, type 2 diabetes and gestational diabetes can often be prevented or delayed.

Preventing Type 2 Diabetes

For people with prediabetes, lifestyle changes can significantly reduce the risk of developing type 2 diabetes. Studies show that lifestyle modification programs can reduce diabetes risk by about 29% (39). Another comprehensive analysis found similar benefits from lifestyle interventions for people with prediabetes (40).

Key prevention strategies include:

  • Losing 5-7% of body weight if overweight
  • Getting at least 150 minutes of physical activity per week
  • Eating a healthy diet
  • Managing stress

Even small amounts of weight loss help. In the cases of overweight and obesity, losing 5-10% of one’s body weight reduces the risk of type 2 diabetes. Research illustrates that the amount of weight lost (in the range of 1-9%) is directly proportional to the risk reduction of prediabetes progressing to type 2 diabetes (39). The more weight lost, the lower the diabetes risk.

Screening and Early Detection

Regular screening helps identify diabetes and prediabetes early.

  • Adults who are overweight or obese should be screened between ages 40-70 (16).
  • Earlier screening is recommended for people with additional risk factors.
  • Women who had gestational diabetes should be tested regularly after pregnancy.

Early detection is important because many people with diabetes don’t know they have it. About half of all people with diabetes worldwide are undiagnosed (6).

Managing Risk After Gestational Diabetes

Women who have had gestational diabetes need ongoing monitoring and prevention efforts. They should:

  • Get tested for diabetes 6-12 weeks after delivery
  • Continue testing every 1-3 years
  • Maintain a healthy weight
  • Stay physically active
  • Consider breastfeeding, which may reduce diabetes risk

Living with Diabetes

Managing diabetes requires ongoing care and attention, but people with diabetes can live long, healthy lives with proper management.

Daily Management

Daily diabetes management includes:

  • Monitoring blood sugar levels
  • Taking medications as prescribed
  • Eating regular, balanced meals
  • Staying active
  • Managing stress
  • Getting enough sleep

People with type 1 diabetes may experience fatigue more often than those without diabetes. Understanding and managing fatigue is an important part of diabetes care (41).

Education and Support

Diabetes self-management education and support are crucial for successful management. Education helps people understand their condition and make informed decisions about their care. Support from healthcare providers, family, and diabetes support groups can improve outcomes.

Regular Health Monitoring

People with diabetes need regular check-ups to monitor for complications:

  • A1C tests (blood sugar average over 2-3 months)
  • Blood pressure checks
  • Cholesterol tests
  • Eye exams
  • Foot exams
  • Kidney function tests

When to See Your Healthcare Provider

If you don’t have diabetes

See your doctor if you experience symptoms, like excessive thirst, frequent urination, unexplained weight loss, or extreme fatigue. You should also get screened if you have risk factors for diabetes.

If you have diabetes

Regular appointments with your diabetes care team are essential. See your provider immediately if you experience:

  • Signs of very high blood sugar (confusion, excessive thirst, or frequent urination)
  • Signs of low blood sugar that doesn’t improve with treatment
  • Wounds that won’t heal
  • Signs of infection
  • Chest pain or shortness of breath
  • Any sudden changes in vision

Between regular appointments, contact your provider if you’re having trouble managing your blood sugar or if you have questions about your treatment plan.

Conclusion

Diabetes is a complex condition that affects millions of people worldwide. While it requires ongoing management, advances in treatment and our understanding of the disease continue to improve outcomes. Type 1 diabetes requires lifelong insulin therapy, while type 2 diabetes can often be managed with lifestyle changes and medications. Gestational diabetes requires careful monitoring during and after pregnancy.

Prevention is possible for type 2 diabetes through healthy lifestyle choices. Early detection and proper management can prevent or delay complications. If you have risk factors for diabetes or associated symptoms (like excessive thirst, frequent urination, or unexplained weight loss), talk to your healthcare provider about screening.

With proper care, education, and support, people with diabetes can manage their condition effectively and maintain a good quality of life. Regular monitoring, medication adherence, and healthy lifestyle choices are key to successful diabetes management.

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