ConditionHormones & metabolism
Type 2 Diabetes
Type 2 diabetes is a long-term condition in which blood sugar stays too high because the body resists insulin and the pancreas cannot make enough extra to compensate. It accounts for about 90% to 95% of diabetes and usually develops gradually in adults, often with no symptoms for years. It is diagnosed with an A1C of 6.5% or higher. Weight loss, activity and modern medicines control it well, prevent most complications and, for some people, bring it into remission.
Also called: Type 2 diabetes mellitus, T2DM, adult-onset diabetes, non-insulin-dependent diabetes, NIDDM
At a glance
- What it is
- High blood sugar from insulin resistance plus a gradual decline in insulin production.
- Who gets it
- Mostly adults over 35, but increasingly teens and young adults; strongly linked to excess weight, inactivity and family history.
- Diagnosis
- A1C 6.5% or higher, fasting glucose 126 mg/dL (7.0 mmol/L) or higher, or a 2-hour glucose test of 200 mg/dL (11.1 mmol/L) or higher.
- Treatment
- Lifestyle change, metformin, GLP-1 or SGLT2 medicines, and insulin if needed.
- Targets
- A1C under 7% for most adults, plus blood pressure and cholesterol control.
When to get help
Call 911 or go to the ER
- Confusion, extreme drowsiness, severe dehydration or very high readings (over about 600 mg/dL or 33 mmol/L), which can mean hyperosmolar hyperglycemic state
- Vomiting, belly pain, fast breathing or fruity-smelling breath, especially on an SGLT2 medicine, which can mean ketoacidosis even with near-normal glucose
- Low blood sugar with confusion, seizure or unconsciousness, or that does not improve after treatment
- Chest pain, stroke symptoms, or a foot that is cold, pale or turning black
See a doctor within a day or two
- Blood sugar consistently above 300 mg/dL (16.7 mmol/L)
- A foot sore, blister or wound that is red, swollen, draining or not healing
- Frequent lows (below 70 mg/dL or 3.9 mmol/L) on insulin or sulfonylureas
- Sudden blurred vision or new floaters
Book a routine appointment
- Thirst, frequent urination, fatigue or recurring infections without a diagnosis
- No A1C check in the past 6 months, or no eye, foot or kidney check in the past year
- Numbness or tingling in the feet
How type 2 diabetes develops
Two problems combine:
- Insulin resistance: muscle, fat and liver cells respond poorly to insulin, mainly because of excess fat in the abdomen and liver, inactivity and genetics.
- Failing beta cells: the insulin-making cells in the pancreas first compensate by working harder, then gradually lose function.
Blood sugar rises slowly, through a prediabetes stage, often over 5 to 10 years. By diagnosis, many people have already lost a substantial share of beta-cell function. Unlike type 1 diabetes, there is no autoimmune attack, and the body still makes insulin, often more than normal at first.
Type 2 diabetes symptoms
Many people have no symptoms and are diagnosed through routine blood tests. When symptoms occur, they build slowly:
- Increased thirst and dry mouth
- Frequent urination, including at night
- Tiredness
- Blurred vision that comes and goes
- Slow-healing cuts and sores
- Frequent infections: yeast infections, urinary tract infections, skin infections
- Tingling or numbness in the feet
- Unexplained weight loss, when sugar is very high
- Dark, velvety skin in body folds (acanthosis nigricans), a sign of insulin resistance
Some people first learn they have type 2 diabetes when a complication appears, such as eye changes found at an optometrist or a foot ulcer.
Causes and risk factors
- Overweight or obesity, especially around the waist
- Physical inactivity
- Family history: a parent or sibling with type 2 diabetes
- Age over 35, though rates in young people are rising
- Black, Hispanic/Latino, American Indian, Alaska Native, Asian American and Pacific Islander ancestry
- History of gestational diabetes or a baby over 9 lb (4 kg)
- Polycystic ovary syndrome
- High blood pressure, low HDL or high triglycerides (metabolic syndrome)
- Short sleep, smoking and some medicines, such as steroids and some antipsychotics
The ADA recommends screening every adult from age 35, and earlier for overweight adults with additional risk factors.
Diagnosis: A1C and glucose numbers
| Test | Normal | Prediabetes | Type 2 diabetes |
|---|---|---|---|
| A1C | Below 5.7% | 5.7% to 6.4% | 6.5% or higher |
| Fasting glucose | Below 100 mg/dL (5.6 mmol/L) | 100 to 125 mg/dL | 126 mg/dL (7.0 mmol/L) or higher |
| 2-hour glucose tolerance test | Below 140 mg/dL (7.8 mmol/L) | 140 to 199 mg/dL | 200 mg/dL (11.1 mmol/L) or higher |
| Random glucose with symptoms | 200 mg/dL (11.1 mmol/L) or higher |
Without clear symptoms, an abnormal result is confirmed with a repeat test. A1C can be misleading with anemia, recent blood loss, pregnancy, kidney failure and some hemoglobin variants. If someone is young, thin or has very rapid symptoms, doctors may test for antibodies to rule out type 1 or latent autoimmune diabetes.
Treatment for type 2 diabetes
Treatment is personalized: goals and medicines depend on your age, weight, heart and kidney health, risk of low blood sugar, cost and preferences.
Lifestyle: the foundation
- Weight loss: losing 5% to 10% of body weight improves blood sugar, blood pressure and cholesterol; losing 15% or more can lead to remission.
- Physical activity: at least 150 minutes a week of moderate activity plus strength training 2 to 3 times a week. A walk after meals lowers post-meal spikes.
- Eating pattern: no single diet is best. Emphasize vegetables, legumes, whole grains, fruit, nuts, fish and lean protein; cut sugary drinks, refined starches and ultra-processed foods. Lower-carbohydrate, Mediterranean and plant-based patterns all have evidence.
- Diabetes self-management education: structured classes improve A1C and confidence.
- Stop smoking, and limit alcohol, which can cause lows with some medicines.
Type 2 diabetes medications
| Medicine class | Examples | How it helps | Notes |
|---|---|---|---|
| Biguanide | Metformin | Reduces glucose made by the liver | Inexpensive, weight-neutral; stomach upset early; can lower B12 |
| GLP-1 receptor agonists | Semaglutide, dulaglutide, liraglutide | Boost insulin after meals, reduce appetite | Significant weight loss; proven heart benefit; nausea common |
| Dual GIP/GLP-1 agonist | Tirzepatide | As above, stronger effect | Largest A1C and weight reductions among non-insulin drugs |
| SGLT2 inhibitors | Empagliflozin, dapagliflozin, canagliflozin | Kidneys pass extra glucose in urine | Protect heart and kidneys; genital yeast infections; rare ketoacidosis |
| DPP-4 inhibitors | Sitagliptin, linagliptin | Mild boost to insulin | Well tolerated, weight-neutral, modest effect |
| Sulfonylureas | Glipizide, glimepiride | Push the pancreas to release insulin | Cheap; can cause lows and weight gain |
| Thiazolidinedione | Pioglitazone | Improves insulin sensitivity | Helps fatty liver; fluid retention, weight gain |
| Insulin | Basal (glargine, degludec) and mealtime insulins | Replaces insufficient insulin | Most powerful; needs glucose monitoring; risk of lows |
Heart and kidney protection now drives many choices. For people with heart disease, heart failure or chronic kidney disease, the ADA recommends an SGLT2 inhibitor and/or a GLP-1 receptor agonist with proven benefit, regardless of A1C. For people who need weight loss, GLP-1 medicines or tirzepatide are often preferred.
Needing insulin does not mean you have failed. Type 2 diabetes is progressive, and many people eventually need it.
Treatment targets
- A1C: under 7% for most adults; tighter (around 6.5%) for some younger people if safe, looser (under 8%) for older adults or those with frequent lows or limited life expectancy
- Fasting and pre-meal glucose: 80 to 130 mg/dL (4.4 to 7.2 mmol/L)
- Blood pressure: under 130/80 mm Hg
- Cholesterol: a statin for most adults aged 40 to 75 with diabetes
Monitoring blood sugar
People on insulin benefit from glucose meters or continuous glucose monitors (CGMs). CGMs are increasingly used by people on non-insulin medicines too, showing how food, activity and sleep affect glucose. Time in range (70 to 180 mg/dL) of over 70% is a common goal.
Low blood sugar (hypoglycemia)
Mainly a risk with insulin and sulfonylureas. Symptoms are shakiness, sweating, hunger, fast heartbeat, irritability and confusion. Follow the 15-15 rule: take 15 grams of fast sugar (4 ounces of juice or regular soda, or glucose tablets), recheck in 15 minutes and repeat if still below 70 mg/dL (3.9 mmol/L). See hypoglycemia.
Complications
Years of high blood sugar damage large and small blood vessels and nerves:
- Heart attack and stroke: the leading cause of death in type 2 diabetes
- Eye disease: diabetic retinopathy, cataracts, glaucoma
- Kidney disease: diabetic nephropathy
- Nerve damage: peripheral neuropathy with numbness and pain, and autonomic problems such as gastroparesis and erectile dysfunction
- Foot ulcers and amputation: see diabetic foot
- Gum disease, infections, fatty liver, hearing loss and cognitive decline
- Acute emergencies: hyperosmolar hyperglycemic state and, less often, ketoacidosis
Your yearly checklist
- A1C every 3 to 6 months
- Blood pressure at every visit
- Dilated eye exam or retinal photos every 1 to 2 years
- Kidney tests: blood creatinine (eGFR) and urine albumin-to-creatinine ratio at least yearly
- Comprehensive foot exam at least yearly, plus daily self-checks
- Cholesterol panel
- Dental checkups twice a year
- Vaccines: flu, COVID-19, pneumococcal, hepatitis B, and others as advised
Can type 2 diabetes be reversed?
Type 2 diabetes can go into remission, defined as an A1C below 6.5% for at least 3 months without glucose-lowering medicines. It is not called a cure, because blood sugar can rise again if weight returns.
- In the DiRECT trial, almost half of participants following a structured low-calorie diet program were in remission at 1 year, and the chance was highest in those who lost 33 lb (15 kg) or more.
- Bariatric surgery leads to remission in a large share of people with obesity.
- Remission is more likely early, within the first few years after diagnosis, while beta cells still work.
Even without remission, meaningful weight loss reduces medication needs and complication risk.
Living with type 2 diabetes
- Plan meals around non-starchy vegetables, protein and fiber-rich carbohydrates.
- Build activity into each day, including short walks after meals.
- Check your feet daily and wear well-fitting shoes.
- Know your sick-day rules: on days you cannot eat or drink normally, your doctor may advise pausing metformin or SGLT2 inhibitors.
- Diabetes distress and depression are common; ask for help if managing diabetes feels overwhelming.
Frequently asked questions
What are the early signs of type 2 diabetes?
Early signs include increased thirst, frequent urination, tiredness, blurred vision, slow-healing sores and frequent infections. Many people have no symptoms at all, which is why screening from age 35, or earlier with risk factors, is recommended.
What A1C level means type 2 diabetes?
An A1C of 6.5% or higher on two tests, or with other confirming results, means diabetes. An A1C from 5.7% to 6.4% is prediabetes, and below 5.7% is normal. Most adults with diabetes aim to keep their A1C below 7%.
Can type 2 diabetes be reversed?
It can go into remission, meaning normal-range A1C without diabetes medicines, usually after substantial weight loss through diet programs, medicines or bariatric surgery. Remission is most likely in the first years after diagnosis. It needs maintaining, because blood sugar can rise again with weight regain.
What is the first medication for type 2 diabetes?
Metformin is often the first medicine because it is effective, safe, inexpensive and does not cause weight gain or low blood sugar on its own. However, people with heart disease, heart failure, kidney disease or obesity may start with or add a GLP-1 receptor agonist or an SGLT2 inhibitor for their organ-protecting benefits.
Is type 2 diabetes caused by eating sugar?
Not directly. Type 2 diabetes results from insulin resistance and declining insulin production, driven by excess body fat, inactivity, genetics and age. Diets high in sugary drinks and refined carbohydrates contribute to weight gain and raise risk, but eating sugar alone does not cause it.
What is the difference between type 1 and type 2 diabetes?
Type 1 is an autoimmune disease in which the body destroys its insulin-making cells, so insulin is needed from diagnosis. Type 2 is caused by insulin resistance and gradual loss of insulin production and is often managed initially with lifestyle and tablets or injections other than insulin. See our general diabetes guide for comparison.
Sources
This guide was written from current patient and clinical guidance, including:
- American Diabetes Association: Standards of Care in Diabetes (current edition)
- CDC: Type 2 diabetes
- NIDDK: Type 2 diabetes
- ADA/EASD: Management of Hyperglycemia in Type 2 Diabetes consensus report
- Diabetes Remission Clinical Trial (DiRECT), Lean MEJ et al, The Lancet 2018