Type 2 diabetes

Type 2 diabetes is the most common form of diabetes mellitus, a group of health conditions linked to having high blood sugar, also known as hyperglycemia. When you have type 2 diabetes, your body can’t effectively process the glucose (sugar) in your blood that provides energy to your body’s cells. This causes you to have chronically high blood sugar levels. 

The two other main conditions under the diabetes umbrella are type 1 diabetes and gestational diabetes, which affects a person during pregnancy. 

Type 2 diabetes accounts for 90 to 95 percent of all diabetes cases in the United States. That’s upwards of 35 million U.S. adults and children living with the disease today. 

Type 1 vs. type 2 diabetes: What's the difference? 

Type 1 and type 2 diabetes both disrupt the way your body processes (or metabolizes) blood sugar, although they have distinct causes. Both diabetes types cause your blood sugar levels to rise.  

Type 1 diabetes is considered an autoimmune condition. When you have type 1 diabetes, your body’s immune cells attack your pancreas, preventing it from making enough of the hormone insulin, which regulates your blood sugar levels. For this reason, the disease was formerly known as insulin-dependent diabetes. 

Type 2 diabetes occurs chiefly because of insulin resistance. Your body makes enough insulin early in the course of the disease, but it can’t effectively use the hormone to transport blood sugar to your cells. 

Type 1 diabetes was also previously called juvenile-onset diabetes because it often develops during childhood. Type 2 diabetes used to be known as adult-onset diabetes because it tended to appear first in adulthood. These terms have changed, however, because type 2 diabetes can affect children and teens in addition to adults and because type 1 diabetes may occur at any age.  

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You may not notice any symptoms of type 2 diabetes early on. That’s because type 2 diabetes tends to progress slowly and quietly, much like other long-term health conditions such as high blood pressure.  

Hyperglycemia (high blood sugar) symptoms 

When you have hyperglycemia, your blood sugar level rises above: 

• 125 milligrams per deciliter (mg/dL) while fasting (not eating) 
• 180 mg/dL two hours postprandial (after having a meal) 

Early signs and symptoms of type 2 diabetes due to high blood sugar might include: 

• Blurry vision 
• Feeling tired or weak 
• Feeling hungry or thirsty more often 
• Frequent urination 
• Sudden, unexplained weight loss 
• Headaches 
• Infections that occur more often; these include wounds that heal slowly and urinary tract infections (UTIs) 
• Very dry mouth 

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Type 2 diabetes disrupts the way your body uses blood sugar. This can lead to issues with the way your body stores and uses fat and other energy sources. The condition is caused by several factors, which may include: 

• Insulin resistance 
• Overweight/obesity and physical inactivity 
• Genes and family history 

How does insulin resistance contribute to type 2 diabetes? 

The body's inability to respond to circulating insulin levels is known as insulin resistance. The condition makes it difficult for your body’s cells to function efficiently.  

Ordinarily, blood sugar is your body’s go-to energy source: It’s readily available and works quickly to fuel your cells. Insulin helps transport that blood sugar into your body’s cells to use as energy. When insulin resistance occurs, insulin becomes less effective and your body can’t keep your blood sugar level balanced.  

As your body grows more resistant to insulin, your pancreas responds by releasing greater amounts of insulin to help move glucose into your cells and to bring your blood sugar levels down. But when you have type 2 diabetes, your body becomes less sensitive to the effects of insulin and eventually stops responding to normal and even excessive levels of the hormone. Elevated levels of insulin is known as hyperinsulinemia.  

As the disease progresses, cells in the pancreas called beta cells that make insulin either die or wear out. Your pancreas can therefore no longer make enough insulin to overcome this resistance and satisfy your body’s energy needs. 

How does being overweight or obese contribute to type 2 diabetes? 

Being overweight or obese, combined with a lack of physical activity, tops the list of factors that contribute to type 2 diabetes that are at least in part preventable.  

Belly fat that accumulates in the deeper layers of your midsection and surrounds your internal organs is known as visceral fat. This excess weight and fat can trigger insulin resistance. Excess body fat can also boost fatty acid levels in your blood. A build-up of these fatty acids in your liver impairs liver function, including the organ’s ability to produce and store blood sugar for current and future energy demands. 

Even if you fall within what may be considered a healthy range of body mass index (BMI), carrying extra visceral fat can increase your body’s demands for insulin, which raises your blood sugar levels.  

BMI measures body fat based on your height and weight (although it’s only one measure commonly used for this purpose and is not always a perfect measure of one’s overall health). Based on BMI alone, you’re considered overweight if your BMI is over 25 and obese if your BMI is over 30. 

How do genes contribute to type 2 diabetes? 

Carrying certain genes may make you more likely to develop type 2 diabetes. Members of certain racial and ethnic groups also carry a higher risk of type 2 diabetes for reasons not fully understood.  

According to the Centers for Disease Control and Prevention (CDC), the percentage of U.S. adults diagnosed with type 2 diabetes varies by race and ethnicity as follows: 

• American Indian or Alaska Native: 14.5 percent 
• Black, non-Hispanic: 12.1 percent 
• Hispanic overall: 11.8 percent 
• Asian, non-Hispanic: 9.5 percent 
• White, non-Hispanic: 7.4 percent 

There may also be a genetic component to one’s risk of developing obesity, which also contributes to the development of type 2 diabetes. 

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Around 95 percent of the time, obesity and lack of exercise are the main reasons the body doesn’t use insulin efficiently, according to a 2023 review of studies published in the Journal of Clinical Medicine.  

Other type 2 diabetes risk factors include: 

• Prediabetes: When you have prediabetes, your blood sugar levels tend to be higher than normal but not high enough for a type 2 diabetes diagnosis. It’s often a precursor to diabetes when left untreated. As many as 96 million Americans aged 18 and older (or 38 percent of the U.S. adult population) had prediabetes as of 2019, according to figures from the CDC.  
• Family history: The fact that type 2 diabetes tends to run in families may involve genetics or it may be a result of habits shared by family members that can increase their risk. 
• Age: Your risk goes up once you’re over 35 years old, although anyone at any age can develop type 2 diabetes. 
• Blood cholesterol levels: Having high triglycerides (blood fats) and low levels of high-density lipoprotein (aka HDL or “good” cholesterol) are associated with an increased risk. 
• Eating habits: Studies have shown that risk increases with excessive intake of foods and drinks that are high in calories and low in nutrients, such as red and processed meats, refined grains, and foods and drinks with added sugar.  
• Too much sitting: Multiple studies have shown that physical inactivity raises the risk of type 2 diabetes, obesity, and other health issues. 
• Pregnancy-related risks: Having gestational diabetes or giving birth to a baby that weighs more than 9 pounds raises the risk. 
• Sleep habits: Your body produces more of the stress hormone cortisol when you don’t get enough quality sleep. This not only has the rebound effect of making it harder to sleep, it also impedes insulin production and your body’s response to insulin, which can contribute to the development of type 2 diabetes. 
• Polycystic ovary syndrome: People with polycystic ovary syndrome (PCOS) typically have elevated levels of the hormone androgen. This may contribute to insulin resistance, as well as acne, irregular menstrual cycles, and weight gain. 
• Acanthosis nigricans: The skin condition causes patches of thick, darkened skin with a velvet-like texture around areas of the body with skin folds, such as the armpit, knuckles, and neck. In some instances, this is a sign of insulin resistance. 

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Your HCP will order lab tests to confirm or rule out a type 2 diabetes diagnosis. These may include:  

• Fasting plasma glucose test (FPGT): A result of 126 mg/dL or higher on two separate occasions indicates type 2 diabetes. FPGT measures your blood sugar level after you’ve fasted for at least eight hours (no eating or drinking, except for sips of water). 
• Hemoglobin A1C (HbA1C): A result of 6.5 percent or higher on two separate days indicates type 2 diabetes. HbA1C measures your average blood sugar levels over a 2- to 3-month period. 
• Oral glucose tolerance test (OGTT): A result of 200 mg/dL indicates type 2 diabetes. Your blood sugar levels are tested before the OGTT and two hours after you drink a special glucose beverage to assess how your body handles glucose. 
• Random plasma glucose test (RPGT): This test measures your blood sugar level without fasting beforehand. A result of 200 mg/dL or higher is associated with symptoms of hyperglycemia or a hyperglycemic crisis. Usually, your HCP will use a second test to confirm you have type 2 diabetes. 

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Over time, high blood sugar and insulin levels can lead to health complications that may affect various body systems:  

Brain: High blood sugar and impaired metabolism of blood sugar, insulin resistance, and hyperinsulinemia can speed cognitive decline and raise the risk of dementia types such as Alzheimer’s disease (AD), according to a 2022 review of studies published in Biomedicines. Because of significant ties found between type 2 diabetes and the brain disorder, some experts and researchers refer to AD as “type 3 diabetes” or “diabetes of the brain.” 

Eyes: Damage to the blood vessels at the back of your eyes, called diabetic retinopathy, can lead to other eye conditions such as diabetic macular edema (swelling) and blindness. You may also be twice as likely to develop glaucoma and 2 to 5 times more likely to develop cataracts. 

Heart and blood vessels: Type 2 diabetes has been linked to atherosclerosis (narrowing of your blood vessels), heart disease, high blood pressure, and stroke. 

Hearing: Diabetes can damage structures and nerves within your inner ears, causing dizziness, tinnitus, and hearing loss, likely due to impaired metabolism of blood sugar. In fact, the rate of hearing loss is twice as high in people with diabetes and 30 percent higher in those with prediabetes, according to a 2021 review of studies published in Ageing Research Reviews.

Gums: If you have type 2 diabetes, you’re more likely to have gum diseases such as mild gum inflammation (gingivitis) or breakdown of the bones and connective tissues that hold your teeth in place (periodontitis). The relationship goes both ways: Having periodontitis raises the risk of type 2 diabetes by 27 to 53 percent, according to a 2022 review of studies published in Frontiers in Immunology. 

Kidneys: Type 2 diabetes can lead to chronic kidney disease and kidney failure, called end-stage renal disease (ESRD). ESRD requires long-term treatment with dialysis or a kidney transplant. 

Nerves: Type 2 diabetes can cause diabetic neuropathy (nerve damage) in your limbs, bladder, eyes, digestive system, reproductive organs, sweat glands, eyes, and other parts of your body. This can lead to health issues such as carpal tunnel syndrome, foot ulcers, irregular heart rhythms, sexual problems including erectile dysfunction and painful sex, and, in extreme cases, amputation of affected limbs. 

Skin: Your risk for skin infections may also be higher and wounds may heal slowly. 

Sleep: Many reviews of studies have found a strong link between type 2 diabetes and obstructive sleep apnea (OSA), which causes periodic pauses in your breathing while you sleep. The more severe OSA gets, the harder it is to keep your blood sugar levels balanced. OSA causes sudden drops in your blood oxygen level (called hypoxia or hypoxemia), straining your heart and lungs and raising your risk of serious and sometimes fatal conditions such as high blood pressure, heart attack, stroke, irregular heartbeats such as atrial fibrillation, and cardiac arrest stemming from these abnormal heart rhythms. 

Can type 2 diabetes raise the risk of cancer? 

People with type 2 diabetes have a 1.5-fold higher risk of various cancers, according to a 2021 review of studies published in Biomedicines. These include: 

• Breast cancer 
• Colorectal cancer 
• Ovarian cancer 
• Pancreatic cancer 

Hyperinsulinemia may promote the growth and survival of cancer cells. It may also prompt cancer cells to metastasize, or spread to other parts of the body. 

Hyperglycemia may also damage your DNA and induce oxidative stress, which can cause tumors to form. Oxidative stress occurs when your body doesn’t have enough protective molecules called antioxidants to counteract the effects of harmful molecules called free radicals.  

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Be sure to get prompt medical care if you’re having new, severe, or persistent type 2 diabetes symptoms. You should also be alert to symptoms of the following: 

Hypoglycemia (low blood sugar) 

While chronically high blood sugar levels can damage the body over time, untreated hypoglycemia can become a medical emergency. For people being treated for type 2 diabetes, hypoglycemia may be a side effect of diabetes medicines and may be influenced by how much insulin you take and when you take it.  

People with type 2 diabetes may experience low blood sugar for other reasons, as well, including: 

• Not getting enough carbohydrates from the foods you eat or drink, or skipping or delaying meals 
• Drinking too much alcohol without eating enough food 
• Fasting, which you might do as preparation for a medical procedure, while you continue to take medicines that lower your glucose level 
• Exercising more than usual, which can lower blood glucose levels for up to 24 hours after a workout 
• Being sick, which can cause you to eat less than you normally do, thereby lowering your blood sugar level 

You can become hypoglycemic if your blood sugar drops below typical levels, or under 70 mg/dL. What’s considered too low may vary for each person.  

Many people don’t have symptoms until their blood sugar levels drop below 55 mg/dL. At this point, you may not feel well enough to check your blood sugar or treat it by yourself, depending on which hypoglycemia symptoms you have. In this case, it’s important to get proper medical care without delay. 

Symptoms of low blood sugar may include: 

• Anxiety 
• Blurry vision 
• Confusion or trouble thinking 
• Dizziness or lightheadedness 
• Fast heartbeat 
• Headache 
• Hunger 
• Irritability or moodiness 
• Loss of consciousness 
• Skin tingling 
• Sweating 
• Tiredness, weakness, or drowsiness 
• Tremors 
• Trouble speaking 

Diabetic ketoacidosis 

Diabetic ketoacidosis (DKA) is a serious and potentially life-threatening complication of diabetes. Although it occurs more often in people with type 1 diabetes, about 10 to 30 percent of the time it occurs in people with type 2 diabetes when they’re under extreme physical stress or acutely ill. 

DKA happens when your blood sugar can’t enter your cells to be used for energy because your body doesn’t have enough insulin to support this process. Your liver produces acids called ketones to break down fat to fuel your body’s energy demands instead. 

In the case of DKA, your body makes too many ketones too fast. As a result, ketone levels climb to toxic levels because your body can’t break them down and use them for energy fast enough. 

Adults with DKA may also have blood sugar levels higher than 250 mg/dL. Children’s blood sugar may spike above 200 mg/dL to above 1000 mg/dL. 

At first, you may only feel very thirsty or urinate more often, but severe DKA symptoms can develop quickly. These may include: 

• Fruity-scented breath (sometimes called acetone breath because it can smell like the fruity scent of nail polish remover made with this compound) 
• Feeling confused or having difficulty keeping your thoughts focused 
• Dry or flushed skin 
• Feeling constantly tired 
• Fast, deep breaths or shortness of breath 
• Headache 
• Nausea or vomiting 
• Stiff or achy muscles 
• Stomach pains 

Diabetic coma 

Without prompt treatment, DKA can cause you to lose consciousness. This is known as a diabetic coma. 

Very high and very low blood sugar levels can also cause you to lapse into a diabetic coma. You’ll usually experience severe hyperglycemia or hypoglycemia symptoms before this happens. 

Hyperosmolar hyperglycemic state (or syndrome) 

Hyperosmolar hyperglycemic state (HHS) is a life-threatening complication that requires immediate emergency care. HHS occurs mainly in people with type 2 diabetes with very high blood sugar levels. It can cause you to become severely dehydrated and your blood to become highly concentrated (known as having high osmolality) as your body tries to get rid of excess blood sugar. Low insulin levels may also play a role, but your body still makes enough insulin to prevent ketones from being produced by your liver.  

An underlying health condition can often cause your blood sugar to spike and trigger HHS. These include infections such as pneumonia, sepsis, and UTIs. Sudden and severe conditions that affect your heart and blood vessels can also trigger HHS. These include heart attack, stroke, or a lung artery blood clot called a pulmonary embolism. 

HHS symptoms progress slowly and may take days or weeks to show up. Along with a blood sugar level above 600 mg/dL, you may experience: 

• Blurred or loss of vision 
• Dry mouth 
• Frequent urination 
• Loss of consciousness 
• Mental status changes such as confusion, delirium, and hallucinations 
• Polydipsia (extreme thirst) 
• Weakness or paralysis, which can be worse on one side of your body 

What should I do in the case of type 2 diabetes-related conditions? 

These conditions require emergency medical care. Call 911 or your local emergency number if: 

• You have symptoms that suggest DKA, HHS, or an impending diabetic coma 
• Your hyperglycemia, hypoglycemia, or type 2 diabetes symptoms are severe 
• You feel like you’re going to pass out (if you can, lie down safely before calling for emergency medical care) 
• The person you’re with has lost consciousness (be sure to inform emergency medical staff if they have type 2 diabetes) 

If you don’t have access to a phone, have someone take you to the nearest ER, especially if you feel like you’re going to pass out or don’t feel safe driving yourself. 

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You can usually manage and possibly reverse your type 2 diabetes by making changes to your lifestyle, such as by adopting healthy eating habits and a regular exercise routine. But sometimes your care plan may call for medication or weight-loss surgery. 

Which medications help treat type 2 diabetes? 

Diabetes medicines your HCP may prescribe to help control your blood sugar include the following: 

• Metformin is often the first medicine prescribed. It helps your liver make less glucose and improves insulin sensitivity. 
• Alpha-glucosidase inhibitors (AGIs) help lower your blood sugar by slowing down the digestion of certain carbohydrates in the small intestine. These medications (which include acarbose and miglitol) also help block various enzymes that convert complex carbs into simple carbs. 
• Dipeptidyl peptidase-4 (DPP-4) inhibitors (such as sitagliptin, saxagliptin, alogliptin, and linagliptin) help boost insulin secretion and slow the speed at which your gut absorbs glucose. 
• Glucagon-like peptide-1 (GLP-1) agonists (such as exenatide, liraglutide, lixisenatide, and semaglutide) help reduce blood sugar levels, slow digestion, and increase satiety (feeling of fullness when eating), which often means you’ll eat less and lose weight.  
• GLP-1 and glucose-dependent insulinotropic polypeptide (GIP) agonists (such as tirzepatide) activate GLP-1 and GIP receptors to improve blood sugar control. They also help you lose weight by boosting satiety.  
• Sodium-glucose co-transporter-2 (SGLT-2) inhibitors (including canagliflozin, dapagliflozin, empagliflozin, and ertugliflozin) help you excrete glucose in your urine instead of having it return to your bloodstream. 
• Sulfonylureas (such as glyburide, glipizide, glimepiride) and glinides (including repaglinide and nateglinide) stimulate your pancreas to make more insulin. Glinides act faster than sulfonylureas, but their effect is shorter. 
• Thiazolidinediones (including rosiglitazone and pioglitazone) help boost insulin sensitivity, thereby keeping your blood sugar stable. 
• Amylin analogs (including pramlintide acetate) lower blood sugar levels by slowing the speed at which food moves from your stomach to your intestines, decreasing the amount of glucose produced by the liver, and helping you feel full after eating (so you eat less). 

Will you need insulin for type 2 diabetes? 

If lifestyle changes and other medicines aren’t enough to control your blood sugar effectively, your HCP may recommend adding insulin therapy to your type 2 diabetes treatment plan.  

Insulin types can be: 

• Rapid-acting: These take about 15 minutes to start working and stay effective for about 2 to 4 hours. 
• Regular or short-acting: These take about 30 minutes to start working and stay effective for about 3 to 6 hours. 
• Intermediate-acting: These take about 2 to 4 hours to start working and stay effective for around 12 to 18 hours. 
• Long-acting: These take several hours to start working and tend to stay effective for up to 24 hours. 
• Ultra long-acting: These take about 6 hours to start working and stay effective for about 36 hours. 

Your insulin therapy plan may involve a basal-bolus insulin regimen, which entails taking: 

• Basal insulin: This consists of intermediate or long-acting insulin to keep your blood sugar steady during fasting periods such as sleep and in between meals. 
• Bolus insulin: Short-acting or rapid-acting insulin are taken shortly before or just after a meal to quickly bring down your blood sugar levels. 

Insulin can injected into the fatty tissue just under your skin or given through an insulin pump connected to a device that lets you manage how much and how often you get a dose. An inhaled form of insulin is also available in a rapid-acting form that takes about 15 minutes to work but is out of your system in about 180 minutes. 

Can weight-loss surgery reverse type 2 diabetes? 

Type 2 diabetes treatment options may include weight-loss (bariatric) surgery for adults with a BMI of 35 or higher. Although bariatric surgery comes with risks such as nutritional deficiencies and osteoporosis, numerous clinical trials have shown that the procedure can reverse type 2 diabetes in some people who are obese.  

One 2023 review of studies published in Frontiers in Endocrinology noted an 80 percent remission rate in people with type 2 diabetes who had bariatric surgery. Still, the authors warned that bariatric surgery isn’t a surefire cure. Around 20 to 30 percent of people relapse within 10 years of going into type 2 diabetes remission following surgery. 

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Managing type 2 diabetes takes a well-rounded approach and a willingness to make healthy lifestyle changes. Some of these habits may even help prevent type 2 diabetes in the first place. Aim to: 

• Stick with your type 2 diabetes treatment plan, making changes as needed with help from your HCP. At your HCP’s recommendation, you may also add members to your care team, including a certified diabetes nurse educator, registered dietitian nutritionist (RDN), and certified personal trainer. 
• Monitor your blood sugar levels as recommended by your HCP. 
• Get your weekly dose of physical activity. Aim for at least 150 minutes of moderate-intensity cardio, 75 minutes of vigorous-intensity cardio, or a mix of moderate and vigorous cardio each week. Add strength-training activities at least two days a week. Being physically active helps you manage your weight and decrease body fat and increases insulin sensitivity. 
• Avoid sitting for long periods. Try to move around every hour or more for at least a few minutes. 
• Maintain a healthy weight and lose weight, if needed. 
• Get good quality sleep. That’s 7 to 9 hours of deep, restful sleep a day for adults, 8 to 10 hours for teens, and 9 to 12 hours for kids aged 6 to 12 years old. 
• Keep your vaccines current, including your annual flu shot, to lower your risk of infections. High blood sugar can weaken your immune system.  
• Practice self-care, including brushing and flossing your teeth regularly, using stress-management techniques such as yoga and meditation, tending to your mental health needs, and caring for your feet by keeping them clean and moisturized and checking for swelling, sores, and other wounds daily. 
• Quit smoking or never start. Be sure to ask your HCP for help, if needed. 
• Drink alcohol sparingly since it can affect your blood sugar levels. 
• Eat a healthy diet that emphasizes whole foods that are low in fat and added sugars and high in fiber. 

What should a type 2 diabetes meal plan include? 

While there’s no one-size-fits-all diet for type 2 diabetes, studies have shown that certain eating styles can help you reach and maintain your blood sugar goals. For instance, an umbrella review published in 2023 in Nutrients of 30 previously published reviews involving nearly 30,000 participants found that four diets helped lower HbA1C levels most effectively: 

• Mediterranean diet, which focuses on fruits, vegetables, seafood, olive oil, and whole grains 
• Low-carb diet, which can help you stay within your daily carb count range 
• Plant-based diet, which focuses on replacing animal products with plant proteins 
• Low-glycemic index (GI) diet, which recommends low-GI foods such as green veggies, most fruits, chickpeas, lentils, and kidney beans. The plan ranks foods on a scale from 0 to 100 based on their effect on blood sugar levels. 

In general, these eating plans recommend making certain healthy food choices to help you better manage your blood sugar. These include eating whole, nourishing foods such as fiber- and nutrient-rich fruits, veggies, whole grains, and legumes (such as beans and peas), as well as low-fat dairy, fish, and sources of monounsaturated and polyunsaturated fats (such as olive oil and avocado). Foods such as these help with weight loss and improve insulin sensitivity. Sticking to routine mealtimes also helps keep your blood sugar level balanced. 

Eating healthy with type 2 diabetes can be challenging at times. If possible, work with an RDN to tailor a meal plan that helps you better manage your diabetes but also includes your preferred foods and eating style. An RDN can also teach you how to count carbs in each meal and snack, accurately measure food portions, and evaluate food labels. 

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• Everything you need to know about type 2 diabetes
• How to develop your diabetes action plan
• Type 2 diabetes: How often should you test your blood sugar?