Diabetes Center

Diabetes mellitus

Diabetes is a common and serious medical condition. It’s a chronic condition, meaning there’s no treatment that cures it — yet. About 40 million people in the U.S. have diabetes. That’s over 10% of the population.

The official name for diabetes is “diabetes mellitus.” That loosely translates from the ancient Greek as “passing lots of sweet urine.” That’s because in diabetes, sugar (glucose) builds up in the bloodstream and urine.

Let’s review the relationship between insulin and glucose to better understand how diabetes affects the body: 

• Glucose is a type of sugar. It’s the body’s main source of energy. You need it to keep your muscles, brain, heart, and liver working well. The body creates glucose by breaking down the carbohydrates (big sugar chains) you eat and drink. 

• Insulin is a hormone or a chemical messenger in the body made by the pancreas (an organ just below the stomach). Insulin helps the body use and store glucose. But people with diabetes either don’t have enough insulin or their body no longer responds to it. So blood glucose levels can surge after a meal and then drop dangerously at other times.

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Types and causes

Here are the most common types of diabetes. 

Type 1 diabetes

Between 5% and 10% of all people with diabetes have Type 1 diabetes. Type 1 diabetes is an autoimmune disease that affects the cells of the pancreas responsible for making insulin. 

People with this type of diabetes don’t make enough insulin for the body’s needs. Typically, Type 1 diabetes is diagnosed in childhood or early adulthood. 

Type 2 diabetes 

Type 2 diabetes is the most common type: About 90% to 95% of all people with diabetes have Type 2 diabetes. In this type, the body doesn’t respond to insulin normally, and sometimes insulin levels are low. 

People with Type 2 diabetes often develop diabetes gradually over months or even years. Many people who are diagnosed with it have a family history of diabetes. Type 2 diabetes often develops in adults, but it can happen in children too.

Gestational diabetes

Gestational diabetes is when diabetes develops in pregnancy. It can affect the health of the pregnant parent and the baby. It also means you’re at high risk for gestational diabetes in another pregnancy.

Usually, gestational diabetes goes away at the end of the pregnancy. But having it means you’re 10 times more likely to develop Type 2 diabetes in the future. Like prediabetes, gestational diabetes is an opportunity to make lifestyle changes to prevent getting diabetes later in life.

Prediabetes

You might be wondering how prediabetes fits in. Prediabetes is an early form of Type 2 diabetes. Having prediabetes can increase your risk of getting many health complications that are linked with diabetes. But with healthy lifestyle changes, it’s possible to stabilize and even reverse prediabetes.

Less common types of diabetes 

Other types of diabetes are less common and due to other factors. Examples include diabetes caused by: 

• Rare genetic mutations

• Medical conditions like cystic fibrosis and hereditary hemochromatosis

• Hormone imbalances like polycystic ovary syndrome (PCOS), hyperthyroidism, acromegaly, and Cushing’s syndrome

Certain medications can also cause diabetes, such as:

• Corticosteroids

• Some antipsychotic, HIV, and blood pressure medications 

• Immunosuppressants

• Gonadotropin-releasing hormone agonists (used to treat prostate cancer)

• Growth hormones

• Sex hormones 

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Diabetes symptoms

Many people with mild or early diabetes don’t have any symptoms. But some people with diabetes experience: 

• Fatigue

• Extreme hunger or thirst 

• Frequent urination

• Dry mouth

• Blurry vision 

• Headaches

• Numbness or tingling in the hands and feet

Sometimes, these symptoms come on slowly over time and are barely noticeable. Other times, they can make people very sick, very suddenly — especially if they don’t know they have diabetes. 

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Testing for diabetes

You can check for any type of diabetes mellitus with some simple blood and urine tests. Depending on the results, you may need a few tests to help your healthcare team figure out exactly what’s going on. 

If you have symptoms, a healthcare professional will likely do a finger-stick glucose test right there in the office. This is a quick way to measure blood glucose levels. It uses a handheld monitor and only needs a drop of blood. 

They may also do a urine test to look for glucose or ketones in your urine, which normally shouldn’t be there. Both of these tests can give you immediate results. 

If your finger-stick glucose test is high, the healthcare professional may also order a random plasma glucose. This is slightly more accurate than a finger-stick test and requires a blood draw.

If you don’t have symptoms, then they’ll order one (or all) of the following blood tests to screen for or diagnose diabetes.

Fasting blood glucose test

This test requires you to not eat (fast) before the test. That gives a more accurate picture of your blood glucose. Here’s what you need to know:

• You need to be fasting (not eating) for at least 8 hours for this test.

• A normal fasting blood glucose level is less than 100 mg/dL.

Hemoglobin A1C

This test gives a broader picture of your blood glucose. Here are some things to keep in mind:

• You don’t have to be fasting for a hemoglobin A1C (HbA1C or A1C) test.

• An A1C test measures how high your average glucose level has been over the last 3 months.

• A normal A1C level is less than 5.7%.

Oral glucose tolerance test

This test has more steps to follow:

• Usually, you need to be fasting for this one and stay in the lab for 2 hours. 

• You have a blood draw for a baseline glucose level. Then you drink a special sugar drink. After 2 hours, you’ll get your glucose level tested. 

• This measures how your body responds to the sugar challenge in the 2-hour window.

• A normal result is less than 140 mg/dL.

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Treatments

Typically, people with Type 1 diabetes need medications — namely, insulin. This is because people with Type 1 diabetes don’t make enough insulin for their body’s needs. So they need medication that supplements their own low levels of insulin. 

But not everyone with diabetes needs treatment with medications. People with Type 2 diabetes may start with diet and other lifestyle changes. For Type 2 and gestational diabetes, the problem is that the body doesn’t respond normally to insulin. A diabetes-friendly diet and exercise plan can help to reverse this without the need for medication.

Whatever type of diabetes you have, treatment works best when combined with healthy lifestyle changes: 

• Aim to get regular physical activity. 

• Eat a diabetes-friendly diet that’s rich in whole, minimally-processed foods, lean proteins, healthy fats, and fresh fruits and vegetables. The diet should be low in refined sugars, salt, and highly or ultra-processed foods.

These changes might be difficult at first, but they’ll pay off if you can maintain them long term.

As part of your treatment, you’ll also learn to check your blood sugar levels regularly. You’ll have a target range, and it’s important to try and keep your blood glucose levels within that safe range. This will help you avoid complications of diabetes (more on this below).

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Medications

There are three main categories of medications for people with diabetes.

1. Oral medications for diabetes 

These are pill medications you take by mouth. They work in different ways, like: 

• Helping you respond better to your body’s existing insulin

• Increasing how much insulin your body makes in response to a meal 

They’re a treatment for Type 2 diabetes only.

2. Injectable insulins

These can be either: 

• Synthetic (lab-made) insulins

• Insulin analogues (chemical molecules that mimic insulin in the body) 

Injectable insulins work by supplementing the body’s lower-than-normal insulin levels. They can be a treatment for Type 1 and Type 2 diabetes.

3. GLP-1 and GIP/GLP-1 receptor agonists

These are medications like Ozempic, Mounjaro, and others. 

They belong to classes of medications called glucagon-like peptide-1 (GLP-1) receptor agonists and glucose-dependent insulinotropic polypeptide (GIP)/GLP-1 receptor agonists. These medications increase how much insulin the body makes in response to a meal. 

Here are examples of each:

• GLP-1 receptor agonists: Semaglutide (Ozempic, Rybelsus), Victoza (liraglutide), Byetta (exenatide), Bydureon BCise (exenatide), Trulicity (dulaglutide)

• GIP/GLP-1 receptor agonists: Tirzepatide (Mounjaro) 

These medications are only approved for people with Type 2 diabetes.

Choosing a medication

It can take some trial and error to find a treatment approach that works for you and your lifestyle. Your treatment needs will also change over time, as will the new treatments that become available. 

Since this is a treatment you’ll need over the long term, the best treatment for you will also depend on your insurance coverage and what you can afford. Living with diabetes is an expensive business. 

Navigating the ever-changing world of diabetes treatments is complex. Your diabetes care team will help you find a treatment that works for you and your unique situation. Our guides are also a good place to start. 

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Short-term complications

All types of diabetes can make you very unwell. It can be dangerous in both the short and long term when your blood glucose levels get very high or very low.

Hyperglycemia 

Hyperglycemia is when blood glucose levels become very high. People with very high blood glucose levels often need urgent treatment in the hospital. This is especially true if they have a new diagnosis of diabetes or they have diabetes that’s hard to treat. 

For people with Type 1 diabetes, this kind of emergency is called diabetic ketoacidosis (DKA). The body produces high levels of blood acids and becomes very dehydrated. There are similar versions of this emergency that can affect people with Type 2 diabetes. 

Hypoglycemia

Hypoglycemia is when blood glucose levels become very low. That’s a problem because your body needs glucose to survive. Hypoglycemia can cause you to feel very unwell and behave strangely. It’s even possible to black out or have a seizure — among other severe reactions.   

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Long-term complications

Long-term complications develop when blood glucose levels are high and stay high over the course of several years. This is because high levels of glucose in the blood damage blood vessels and nerves throughout the body. 

Diabetes can increase the risk of the following health conditions: 

• Cardiovascular disease: Examples of heart disease are atherosclerosis, coronary artery disease, peripheral artery disease, high blood pressure, heart failure, and stroke.

• Dementia: Examples of dementia include Alzheimer’s disease.

• Chronic kidney disease: This happens when the kidneys aren’t working as they should for 3 months or more.

• Diabetic foot disease: Some examples of diabetic foot disease are numbness (peripheral neuropathy), skin changes, and an increased risk of skin and foot infections. 

• Vision loss: Vision changes from diabetes include cataracts, glaucoma, macular edema, or diabetic retinopathy.

• Dental problems: Diabetes can cause dental issues such as gum disease, tooth decay, tooth loss, infections, and abscesses.

• Infections: These can occur due to a weakened immune system. 

You can’t reverse complications once they set in. But by carefully managing your blood glucose levels, you can stop things from getting worse.

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Preventing complications

Both high and low blood glucose levels can be dangerous to your health. That’s why as part of your diabetes treatment plan, you’ll have a personalized target blood glucose range. 

Most people with diabetes will have times when they over or undershoot their target blood glucose range. That’s to be expected. But it’s likely that the more you can stay in your own target range, the lower your risk of diabetes-related health complications will be. 

You’ll also need to attend regular checkups with your primary care provider or diabetes care team. Screening for diabetes health complications will help you spot problems early — and take steps to curb them. 

If you have diabetes, you’ll learn from your care team about how to prevent short- and long-term complications. 

Here are 12 steps you can start to take now:

1. Take the medication your body needs.

2. Regularly check your blood glucose levels with a glucometer or a continuous glucose monitor (CGM).

3. Learn how to adjust your medication when you’re sick or taking other medication.

4. Learn to prepare diabetes-friendly meals.

5. Avoid or cut back on alcohol.

6. Get help to quit smoking. 

7. Build regular physical activity into your daily routine.

8. See your care team for regular checkups and tests.

9. Learn to recognize the early signs of a diabetic emergency so you can get help. 

10. Try to get good-quality, regular sleep. 

11. Invest in supportive relationships, hobbies, and community.

12. Explore behaviors and/or therapies that improve stress and mental well-being.

These changes may seem overwhelming. But they’re similar to the healthy lifestyle changes that healthcare professionals recommend for anyone trying to improve anything from heart health, weight, and fitness to sleep, immunity, and mental health. In other words, it’s not just your diabetes that will benefit. 

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