Diabetes, medically known as diabetes mellitus, is a chronic metabolic condition that affects how the body regulates blood glucose, commonly called blood sugar. Glucose is the body’s primary source of energy and comes mainly from the food we eat. However, for glucose to enter the body’s cells and provide energy, it requires a hormone called insulin.
Insulin is produced by beta cells in the pancreas. It helps regulate blood sugar by allowing glucose to move from the bloodstream into cells. When the pancreas does not produce enough insulin or the body cannot use insulin effectively, glucose starts accumulating in the bloodstream, resulting in high blood sugar levels.
Over time, persistently elevated blood glucose can damage blood vessels and nerves, affecting several organs, including the heart, kidneys and eyes. If left undiagnosed or inadequately managed, diabetes can increase the risk of heart disease, stroke, kidney failure, vision loss and nerve damage.
According to the World Health Organization (WHO), approximately 830 million people worldwide were living with diabetes in 2022. The burden has increased considerably over the past three decades, with low- and middle-income countries experiencing a particularly rapid rise.
India is among the countries with the highest diabetes burden. According to the International Diabetes Federation’s (IDF) 2025 Diabetes Atlas, an estimated 89.8 million adults aged 20–79 years were living with diabetes in India in 2024. The organisation projects this number could rise to approximately 156.7 million by 2050.
The condition is not limited to older adults. Increasingly, younger adults and even adolescents are being diagnosed with type 2 diabetes, making awareness, early screening and preventive healthcare particularly important.
What are the different types of diabetes?
Diabetes is not a single condition. It is classified into different types depending on the underlying cause and how the body produces or uses insulin.
The four major categories include:
1. Type 1 diabetes
Type 1 diabetes is an autoimmune condition in which the body’s immune system mistakenly attacks and destroys the insulin-producing beta cells in the pancreas. As a result, the body produces little or no insulin.
Although it is frequently diagnosed during childhood and adolescence, type 1 diabetes can develop at any age. Its exact cause is not fully understood, although genetic and environmental factors are believed to contribute.
People with type 1 diabetes require lifelong insulin therapy to survive and regulate their blood glucose levels. It cannot currently be prevented through dietary changes or lifestyle modifications.
Common symptoms include excessive thirst, frequent urination, unexplained weight loss, increased hunger and fatigue. Symptoms may develop rapidly over a few weeks or months.
2. Type 2 diabetes
Type 2 diabetes is the most common form of diabetes, accounting for more than 95% of people living with the condition worldwide, according to WHO.
It develops when the body’s cells become resistant to insulin, a condition known as insulin resistance. Initially, the pancreas attempts to compensate by producing more insulin. However, over time, it may become unable to produce enough insulin to maintain normal blood glucose levels.
Several factors can increase the risk of type 2 diabetes, including:
- Being overweight or having obesity, particularly abdominal obesity.
- Physical inactivity and prolonged sedentary behaviour.
- A family history of diabetes.
- Increasing age.
- Unhealthy dietary patterns.
- A history of gestational diabetes.
- Certain hormonal and metabolic conditions.
Unlike type 1 diabetes, type 2 diabetes can often be prevented or delayed through appropriate lifestyle interventions. Treatment may include dietary changes, regular physical activity, oral medication, injectable medicines and insulin, depending on the individual’s condition.
3. Gestational diabetes
Gestational diabetes is a type of high blood sugar that develops during pregnancy in women who did not previously have diabetes.
During pregnancy, hormonal changes can interfere with the action of insulin, increasing the body’s insulin requirements. When the pancreas cannot produce sufficient insulin to meet these demands, blood glucose levels rise.
What are the early symptoms of diabetes?
Recognising the early warning signs of diabetes is important because timely diagnosis can help prevent complications.
Although symptoms may vary depending on the type of diabetes, some common warning signs include:
1. Frequent urination
One of the most common symptoms of high blood sugar is frequent urination, medically known as polyuria.
When glucose levels become excessively high, the kidneys attempt to remove the excess sugar through urine. This increases urine production, causing a person to visit the bathroom more frequently, including during the night.
2. Excessive thirst
Frequent urination can lead to dehydration, making a person feel unusually thirsty.
This condition, known as polydipsia, may cause someone to drink significantly more water than usual without feeling adequately hydrated.
3. Increased hunger
People with diabetes may experience excessive hunger, medically known as polyphagia.
Although glucose is present in the bloodstream, the body’s cells may not be able to use it effectively because of insufficient insulin or insulin resistance. This can leave the body without adequate energy at the cellular level, triggering increased hunger.
4. Unexplained weight loss
Unexpected weight loss, despite eating normally or experiencing increased hunger, can be an early sign of diabetes.
When the body cannot use glucose effectively, it may begin breaking down stored fat and muscle for energy. This can result in weight loss, particularly in people with untreated type 1 diabetes.
5. Persistent fatigue
High blood sugar can interfere with the body’s ability to use glucose efficiently for energy. Dehydration and associated metabolic changes may also contribute to tiredness.
People may experience persistent fatigue, reduced concentration and difficulty carrying out everyday activities.
6. Blurred vision
High blood glucose can affect the fluid balance in the eyes, temporarily changing the shape of the lens and causing blurred vision.
Persistent or fluctuating vision changes should not be ignored, as diabetes can also damage the small blood vessels in the retina over time.
7. Slow wound healing
People with poorly controlled diabetes may notice that cuts, wounds and skin injuries take longer to heal.
High blood glucose can affect circulation, immune function and nerve health, increasing the risk of infections and delaying tissue repair.
8. Frequent infections
Elevated blood sugar can affect the body’s ability to fight infections. Some people may experience recurrent urinary tract infections, fungal infections, skin infections or genital yeast infections.
9. Tingling or numbness in the hands and feet
Persistent high blood sugar can damage peripheral nerves, leading to diabetic neuropathy.
Early symptoms may include tingling, burning sensations, numbness or pain, particularly in the feet and legs.
Important: Some people with type 2 diabetes do not experience any noticeable symptoms. Therefore, relying only on symptoms to identify diabetes is not advisable. Regular blood glucose screening is important, particularly for people with risk factors.
What causes diabetes?
The causes of diabetes depend on the type of condition. Type 1 diabetes develops when the immune system mistakenly destroys insulin-producing cells in the pancreas. Type 2 diabetes is primarily associated with insulin resistance and progressive impairment in insulin production.
Gestational diabetes develops when hormonal changes during pregnancy increase insulin resistance beyond the body’s ability to compensate. Several factors can contribute to the development of type 2 diabetes.
1. Insulin resistance
Insulin resistance is one of the main underlying mechanisms of type 2 diabetes. It occurs when muscle, fat and liver cells do not respond effectively to insulin. Consequently, glucose cannot enter cells as efficiently, causing blood sugar levels to rise.
2. Excess body weight and abdominal fat
Excess body fat, particularly around the abdomen and internal organs, is associated with insulin resistance. Abdominal obesity is an important metabolic risk factor, including among people who may not appear significantly overweight.
4. Physical inactivity
A sedentary lifestyle can increase the risk of insulin resistance. Regular physical activity helps muscles use glucose more effectively and improves insulin sensitivity. In contrast, prolonged sitting and insufficient movement can contribute to metabolic problems.
5. Unhealthy dietary habits
Dietary patterns that frequently include sugar-sweetened beverages, refined carbohydrates, highly processed foods and excessive calorie intake can contribute to weight gain and metabolic dysfunction.
However, eating sugar alone does not directly cause diabetes. The overall dietary pattern, body composition, genetic predisposition and physical activity levels all influence risk.
What is the difference between normal blood sugar, prediabetes and diabetes?
Blood glucose tests help determine whether a person has normal blood sugar levels, prediabetes or diabetes.
Prediabetes is a condition in which blood glucose levels are higher than normal but not high enough to meet the diagnostic criteria for diabetes.
It indicates an increased risk of developing type 2 diabetes and cardiovascular disease. However, progression is not inevitable. Lifestyle interventions and medical guidance can help delay or prevent the development of type 2 diabetes.
The following are commonly used diagnostic thresholds for non-pregnant adults:
| Blood glucose test | Normal | Prediabetes | Diabetes |
|---|---|---|---|
| Fasting blood glucose | Below 100 mg/dL | 100–125 mg/dL | 126 mg/dL or higher |
| HbA1c | Below 5.7% | 5.7–6.4% | 6.5% or higher |
| 2-hour oral glucose tolerance test | Below 140 mg/dL | 140–199 mg/dL | 200 mg/dL or higher |
A random plasma glucose level of 200 mg/dL or higher, along with typical symptoms of diabetes, can also indicate diabetes.
These thresholds are diagnostic criteria, not personalised treatment targets. A healthcare professional may recommend repeat testing to confirm a diagnosis, particularly when symptoms are absent. Different criteria apply during pregnancy.
How is diabetes treated?
There is no single treatment plan that works for everyone with diabetes. Management depends on the type of diabetes, blood glucose levels, age, overall health, associated medical conditions and individual treatment goals.
The primary objectives are to maintain blood glucose within an appropriate target range, reduce the risk of complications and support long-term quality of life.
1. Lifestyle modifications
Healthy eating, regular physical activity, adequate sleep and weight management form important parts of diabetes care.
2. Oral medications
Several oral medicines are used to manage type 2 diabetes. Metformin is commonly prescribed and works mainly by reducing glucose production in the liver and improving insulin sensitivity.
3. Insulin therapy
Insulin therapy is essential for people with type 1 diabetes because their bodies cannot produce sufficient insulin. It may also be prescribed to people with type 2 diabetes when other treatments are insufficient or when insulin requirements increase during certain medical situations. Insulin can be administered using injections or insulin pumps, depending on the treatment plan.
4. Injectable medicines
Some people with type 2 diabetes may benefit from injectable medicines such as GLP-1 receptor agonists. These medicines can improve blood glucose regulation, and certain medications in this class can also support weight management and reduce cardiovascular risk in eligible patients.
5. Regular blood glucose monitoring
Monitoring blood glucose helps people understand how food, exercise, medication, stress and illness affect their blood sugar. Depending on the treatment plan, doctors may recommend regular finger-prick glucose testing or continuous glucose monitoring (CGM).
What foods should people with diabetes eat?
Diet plays an important role in managing diabetes. However, having diabetes does not mean a person must completely eliminate carbohydrates, rice, fruits or other commonly consumed foods. The goal is to maintain a balanced dietary pattern, manage portion sizes and choose foods that support stable blood glucose levels.
A diabetes-friendly eating pattern may include:
1. Whole grains: Choose whole grains such as oats, whole wheat, millets, barley and brown rice more frequently than highly refined grain products.
2. Fibre-rich vegetables: Include non-starchy vegetables such as spinach, broccoli, cauliflower, beans, cucumber, carrots and gourds.
3. Protein-rich foods: Include pulses, lentils, beans, eggs, fish, lean meat, tofu and unsweetened dairy products, depending on individual dietary preferences.
4. Healthy fats: Include moderate amounts of nuts, seeds and unsaturated vegetable oils.
5. Whole fruits: Choose whole fruits rather than fruit juices. Portion size matters, and fruit intake should be considered as part of the overall carbohydrate intake.
6. Adequate hydration: Drink sufficient water and limit sugar-sweetened beverages, packaged juices and energy drinks.
Foods and beverages to limit
People with diabetes should generally limit:
- Sugar-sweetened beverages and soft drinks.
- Excessive sweets, desserts and confectionery.
- Highly refined carbohydrates.
- Deep-fried and highly processed foods.
- Foods containing excessive amounts of added sugar and unhealthy fats.
There is no universal diabetes diet. A registered dietitian or qualified healthcare professional can help develop a meal plan that considers individual glucose levels, medication, nutritional requirements and cultural food preferences.
Can diabetes be prevented?
Type 1 diabetes cannot currently be prevented through known lifestyle interventions. However, many cases of type 2 diabetes can be prevented or delayed, particularly among people with prediabetes or other risk factors. The following measures can help reduce the risk:
1. Maintain a healthy body weight
Excess body weight, especially abdominal fat, is associated with insulin resistance. For people who are overweight or have obesity, even moderate weight loss can improve insulin sensitivity and reduce the risk of developing type 2 diabetes.
2. Exercise regularly
Regular physical activity helps muscles use glucose more effectively. Adults should aim for at least 150 minutes of moderate-intensity aerobic activity per week, alongside muscle-strengthening activities on two or more days, as appropriate for their health and fitness levels. Brisk walking, cycling, swimming and dancing are examples of activities that can help.
3. Follow a balanced diet
Include fibre-rich foods, vegetables, whole grains, pulses, healthy fats and appropriate protein sources. Limit sugar-sweetened beverages, excessive refined carbohydrates and highly processed foods.
4. Avoid prolonged sitting
Long periods of inactivity can negatively affect metabolic health. Taking short movement breaks, walking after meals and incorporating physical activity into daily routines can help improve glucose regulation.
5. Get adequate sleep
Poor sleep and irregular sleep patterns are associated with metabolic disturbances and insulin resistance. Maintaining a consistent sleep schedule and getting sufficient sleep can support overall metabolic health.
6. Get regular health check-ups
People with a family history of diabetes, abdominal obesity, high blood pressure, PCOS or a history of gestational diabetes should discuss appropriate screening with their healthcare provider. Early identification of prediabetes creates an opportunity to intervene before type 2 diabetes develops.
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