Key points
- Type 2 diabetes develops when the body stops responding well to insulin and, over time, cannot make enough of it to keep blood glucose normal.[3]
- It often causes few or no symptoms at first, so many people find out only through a routine blood test.[4]
- In India, an estimated 101 million adults live with diabetes and a further 136 million have prediabetes.[5]
- Diagnosis is made with laboratory tests: HbA1c, fasting plasma glucose or an oral glucose tolerance test, usually confirmed with a repeat test.[1]
- For people at high risk, sustained lifestyle change cut the chance of developing type 2 diabetes by more than half in a major trial.[7]
Type 2 diabetes is a chronic condition that affects how the body regulates blood glucose, commonly called blood sugar. It can develop gradually and quietly, which is why some people discover it only when they have routine blood tests or see a doctor for something else.
Early detection matters. Appropriate treatment and long-term monitoring reduce the risk of complications affecting the eyes, kidneys, nerves, heart and blood vessels.[6]
What is type 2 diabetes?
Glucose is an important source of energy for the body's cells. After you eat, carbohydrates are broken down into glucose, which enters the bloodstream. Insulin, a hormone made by the pancreas, helps regulate blood glucose and lets many cells use it.
In type 2 diabetes the body develops insulin resistance: cells respond less effectively to insulin. The pancreas may compensate at first by producing more, but over time production may become insufficient, and glucose builds up in the blood. This is called hyperglycaemia.[3]
Type 2 is the most common form of diabetes, but it is not the only one. Type 1 diabetes and other forms have different underlying mechanisms and may need different treatment.[1]
What are the early symptoms of type 2 diabetes?
When symptoms occur, they tend to develop gradually.[4]
1. Frequent urination
When blood glucose rises high enough, the kidneys begin passing excess glucose into the urine, which increases urine production. You may need the bathroom more often, including at night. Frequent urination has other causes too, so it should be read alongside other symptoms.
2. Increased thirst
Passing more urine causes fluid loss, which can leave you unusually thirsty, drinking much more water without feeling hydrated. Persistent thirst with frequent urination deserves a medical assessment.
3. Unexplained weight loss
When glucose cannot be used effectively, the body relies more on stored fat and muscle for energy, and some people lose weight without trying. Unexplained weight loss has several possible causes and should not automatically be put down to diabetes.
4. Increased hunger
Some people feel hungrier because the body is not using glucose well. On its own this is not a reliable sign, but alongside thirst, frequent urination or weight change it is worth asking a doctor about.
5. Fatigue
Changes in glucose regulation, dehydration and associated conditions can all reduce energy. Fatigue has many causes, though, including anaemia, thyroid disorders, poor sleep and stress. Our article on persistent fatigue covers these.
6. Blurred vision
High blood glucose can change the fluid balance within the eye and temporarily blur vision. Sudden visual changes, severe eye pain or significant loss of vision need urgent assessment, not an assumption that diabetes is responsible.
7. Slow-healing wounds and recurrent infections
Persistently high blood glucose can impair the body's normal defence and repair processes, so some people notice recurrent infections or wounds that heal slowly.[4] These are not specific to diabetes.
Can you have diabetes without symptoms?
Yes. Many people have few or no noticeable symptoms when the condition first develops. This is why screening matters for people with risk factors, even when they feel well.[1]
What causes type 2 diabetes?
Type 2 diabetes develops through a combination of genetic, metabolic and environmental factors. No single cause explains every case.[12]
- Insulin resistance. The central feature. If the pancreas cannot keep up with the extra insulin needed, glucose levels rise.
- Family history. A parent, brother or sister with type 2 diabetes increases your risk. It does not make diabetes inevitable, but it makes screening and prevention more important.
- Excess body weight, especially around the abdomen. Associated with greater insulin resistance, although type 2 diabetes also develops in people who are not overweight.
- Physical inactivity. Regular activity helps muscles use glucose and supports insulin sensitivity, even without weight loss.
- Age. Risk rises with age, though type 2 diabetes increasingly appears in younger adults and children. In India, diabetes is a major public health concern across age groups.[5]
- Other factors. Previous gestational diabetes, polycystic ovary syndrome (PCOS), certain medicines and other metabolic conditions.[12]
How is type 2 diabetes diagnosed?
Diagnosis is made through laboratory testing against established clinical criteria. The thresholds below are from the American Diabetes Association and apply to non-pregnant adults.[1][2]
1. HbA1c test
HbA1c measures the proportion of haemoglobin with glucose attached, which reflects your average blood glucose over roughly the previous two to three months. Our short guide explains how to read an HbA1c report.
| HbA1c result | Interpretation |
|---|---|
| Below 5.7% | Below the diabetes threshold |
| 5.7% to 6.4% | Prediabetes range |
| 6.5% or higher | Diabetes threshold |
Without unequivocal hyperglycaemia, a result of 6.5% or higher is usually confirmed by repeat testing or another accepted test. Some forms of anaemia and other red blood cell disorders can make HbA1c less reliable.[1]
2. Fasting plasma glucose
This measures blood glucose after an overnight fast.
| Fasting plasma glucose | Interpretation |
|---|---|
| Below 100 mg/dL | Normal fasting glucose |
| 100 to 125 mg/dL | Prediabetes range (impaired fasting glucose) |
| 126 mg/dL or higher | Diabetes threshold |
Other organisations, including the WHO, use a slightly different range for impaired fasting glucose. A result at the diabetes threshold generally needs confirmation unless the clinical picture is clear.[1]
3. Oral glucose tolerance test
Blood glucose is measured before and two hours after drinking a standard glucose solution. A two-hour result of 200 mg/dL or higher is a diagnostic threshold for diabetes.[1] This test is useful in selected situations when more information is needed.
4. Random plasma glucose
A random result of 200 mg/dL or higher, together with classic symptoms of hyperglycaemia or a hyperglycaemic crisis, can establish the diagnosis.[1] Your doctor will interpret the result in context.
A note on home glucose meters. They are useful for monitoring, but a home reading alone should not be used to diagnose diabetes without a proper clinical assessment.[3]
What is prediabetes?
Prediabetes means blood glucose is above the normal range but below the diabetes threshold. It signals an increased risk of type 2 diabetes, but progression is not inevitable.[2] It usually has no obvious symptoms.
Lifestyle change, weight management where appropriate, regular physical activity and follow-up testing can lower the risk of progression.[7] A doctor can explain your results and suggest a monitoring plan.
What happens if type 2 diabetes is left untreated?
Persistently high blood glucose can damage blood vessels and nerves over time. The risk depends on how long you have had diabetes, glucose control, blood pressure, cholesterol, smoking and other conditions.[6]
- Heart disease and stroke. Diabetes raises cardiovascular risk. Blood pressure, cholesterol and tobacco use need attention alongside glucose.
- Kidney disease. Diabetes can damage the kidneys' filters. Monitoring may include kidney function tests and urine albumin.[13]
- Nerve damage. Diabetic neuropathy can cause tingling, numbness, pain or reduced sensation, particularly in the feet, which makes injuries easier to miss.
- Eye disease. Diabetic retinopathy can begin without symptoms, which is why regular eye examinations matter.[13]
- Foot complications. Reduced sensation and circulation increase the risk of wounds and infection. Get ulcers or worrying changes checked promptly.
How can you reduce your risk of type 2 diabetes?
Not every case can be prevented, but lifestyle change substantially reduces risk for many people. In the US Diabetes Prevention Program, adults at high risk who followed an intensive lifestyle programme had a 58% lower incidence of type 2 diabetes than those given a placebo.[7]
Choose a balanced diet
Build meals around vegetables and whole fruits, whole grains, pulses and other fibre-rich foods, appropriate protein sources, and nuts and seeds in sensible portions. Limit sugar-sweetened drinks and highly processed foods; regular sugary drinks are linked to a higher risk of type 2 diabetes.[9] You do not need to cut out every carbohydrate. Food quality, portion size and your overall pattern matter more.
Exercise regularly
Aim for at least 150 minutes of moderate-intensity activity, such as brisk walking, cycling or swimming, each week.[8] If you have been inactive, start gradually. If you have existing health conditions or complications, ask a doctor what is suitable.
Manage weight where appropriate
For people with excess weight, sustained and achievable weight loss improves metabolic health and lowers risk.[7] Avoid extreme diets and unverified products that promise to reverse insulin resistance quickly.
Prioritise sleep
Poor sleep and some sleep disorders are linked to metabolic risk. Keep a regular schedule, and get checked if you have persistent insomnia, daytime sleepiness or signs of sleep apnoea such as loud snoring.
Get screened when appropriate
Screening can find raised blood glucose before symptoms appear. A doctor can recommend testing based on your age, family history, weight and medical history. Women who have had gestational diabetes may need a more tailored schedule.[1]
How is type 2 diabetes treated?
Treatment is individual and may combine lifestyle change, medicines and regular monitoring.[14]
- Lifestyle. Balanced nutrition, activity, sleep and weight management are the foundation, though they are not enough for everyone.
- Oral medicines. Metformin is commonly used, but it is not the only option. The choice depends on glucose levels, kidney function, heart disease, weight goals and other factors, and some medicines also reduce heart and kidney risk.[14]
- Injectable medicines and insulin. These may be recommended to improve control or meet specific needs. Needing medicine or insulin is not a personal failure. The aim is effective treatment and fewer complications.
- Regular monitoring. HbA1c, blood pressure, cholesterol, kidney tests, eye examinations and foot checks, at a frequency that suits your treatment plan.[13]
Do not stop prescribed medicine or make major changes to treatment without speaking to your doctor.
When should you see a doctor?
Consider a medical assessment if you have:
- persistent increased thirst
- frequent urination, especially at night
- unexplained weight loss
- recurrent blurred vision
- fatigue together with other possible diabetes symptoms
- repeatedly high blood glucose readings
- risk factors such as a strong family history or previous gestational diabetes
When to seek emergency care
Go to the nearest emergency department or call 112 if you develop severe dehydration, repeated vomiting, abdominal pain, deep or rapid breathing, marked drowsiness or confusion, particularly with high blood glucose or known diabetes.
These can be signs of a serious metabolic emergency and should not be managed through online advice or an online consultation.
Frequently asked questions
What are the first signs of diabetes?
Possible early symptoms include frequent urination, increased thirst, fatigue, blurred vision and unexplained weight loss. However, type 2 diabetes can develop without any noticeable symptoms.[4]
Is HbA1c enough to diagnose diabetes?
HbA1c is an accepted diagnostic test when used appropriately. Some conditions affect its accuracy, and a confirmatory test is often needed. A doctor can decide which test suits you.[1]
Can type 2 diabetes be reversed?
Some people achieve remission, particularly after substantial, sustained weight loss. In the DiRECT trial, almost half of participants on a structured weight-management programme were in remission at one year.[10] Remission does not mean diabetes can never return, so ongoing monitoring remains important.[11] Do not stop medicines because your readings improve without discussing it with your doctor.
Does eating sugar directly cause diabetes?
No single food causes type 2 diabetes. Overall diet, excess energy intake, body fat distribution, genetics and activity all influence risk. Frequent sugar-sweetened drinks add to that risk,[9] but eating sugar occasionally does not on its own mean you will develop diabetes.
How often should I get tested?
It depends on your previous results and risk factors. The ADA suggests repeating screening at least every three years when results are normal, and yearly for people with prediabetes.[1] Your doctor can recommend a schedule.
Early detection can make a difference
Type 2 diabetes can develop quietly, but an early diagnosis gives you the chance to address high blood glucose and other heart risk factors before complications develop. Knowing your risk, recognising possible symptoms and getting the right tests are practical steps towards protecting your long-term health.
Talk to a general physician
If you have possible symptoms, a family history of diabetes or a recent report you are unsure about, a general physician can look at your risk and advise whether blood glucose testing is right for you.
References
- American Diabetes Association Professional Practice Committee. 2. Diagnosis and classification of diabetes: Standards of Care in Diabetes—2025. Diabetes Care. 2025;48(Suppl 1):S27–S49. doi:10.2337/dc25-S002
- American Diabetes Association. Diabetes diagnosis. diabetes.org
- National Institute of Diabetes and Digestive and Kidney Diseases. Diabetes tests & diagnosis. niddk.nih.gov
- Centers for Disease Control and Prevention. Diabetes symptoms. cdc.gov
- Anjana RM, Unnikrishnan R, Deepa M, et al. Metabolic non-communicable disease health report of India: the ICMR-INDIAB national cross-sectional study (ICMR-INDIAB-17). The Lancet Diabetes & Endocrinology. 2023;11(7):474–489. doi:10.1016/S2213-8587(23)00119-5
- World Health Organization. Diabetes. Fact sheet. who.int
- Diabetes Prevention Program Research Group. Reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin. New England Journal of Medicine. 2002;346(6):393–403. doi:10.1056/NEJMoa012512
- World Health Organization. Physical activity. Fact sheet. who.int
- Malik VS, Popkin BM, Bray GA, Després JP, Willett WC, Hu FB. Sugar-sweetened beverages and risk of metabolic syndrome and type 2 diabetes: a meta-analysis. Diabetes Care. 2010;33(11):2477–2483. doi:10.2337/dc10-1079
- Lean MEJ, Leslie WS, Barnes AC, et al. Primary care-led weight management for remission of type 2 diabetes (DiRECT): an open-label, cluster-randomised trial. The Lancet. 2018;391(10120):541–551. doi:10.1016/S0140-6736(17)33102-1
- Riddle MC, Cefalu WT, Evans PH, et al. Consensus report: definition and interpretation of remission in type 2 diabetes. Diabetes Care. 2021;44(10):2438–2444. doi:10.2337/dci21-0034
- Centers for Disease Control and Prevention. Diabetes risk factors. cdc.gov
- National Institute of Diabetes and Digestive and Kidney Diseases. Preventing diabetes problems. niddk.nih.gov
- American Diabetes Association Professional Practice Committee. 9. Pharmacologic approaches to glycemic treatment: Standards of Care in Diabetes—2025. Diabetes Care. 2025;48(Suppl 1):S181–S206. doi:10.2337/dc25-S009
