Diabetes is a complex metabolic condition. In 2023, the CDC estimated 136 million people were living with either diabetes or prediabetes, a precursor to the disease. Left untreated, diabetes can lead to serious complications, including heart disease, stroke, nerve damage, blindness, kidney failure, and amputations. Yet nearly 23 percent of U.S. adults (approximately 9 million) remain undiagnosed.
Early detection and proper management of diabetes are crucial in preventing or delaying the onset of complications and improving quality of life for those affected by this condition.
What Is Diabetes?
Diabetes occurs when your blood sugar (glucose) remains too high over a period of time.
When you eat food—a plate of pasta, for instance—it is converted into various nutrients including glucose, your body’s main source of energy. Insulin, a hormone made by the pancreas, helps move glucose from the bloodstream to the body’s cells and tissues.
In someone who doesn’t have diabetes, the pancreas produces enough insulin to move glucose from the blood into cells, keeping blood glucose levels within a normal range. However, in those with diabetes, the pancreas is unable to make enough insulin (type 2 diabetes) or make any at all (type 1 diabetes). As a result, high levels of glucose, unable to enter the cells, build up in the bloodstream. This potentially damages blood vessels and the vital regions they serve—the heart, eyes, kidneys, skin, and nerves.
What Are the Different Types of Diabetes?
There are several forms of diabetes, but the three main ones are type1, type 2, and gestational diabetes.
Type 1 Diabetes
Type 1 diabetes, previously known as insulin-dependent or juvenile diabetes, is a chronic autoimmune condition that prevents the pancreas from producing insulin. It is less common than type 2 diabetes, accounting for 5-10 percent of all diabetes cases in the U.S. (about 1.5 million adults).
With type 1 diabetes, the immune system mistakenly attacks and destroys the insulin-producing beta cells in the pancreas. People with type 1 diabetes must manage their blood sugar levels with insulin injections, an insulin pump, an insulin inhaler, or an automated insulin delivery system. They also need to monitor their blood glucose levels regularly to ensure their treatment plan is working.
While the causes of type 1 diabetes are not entirely understood, scientists have identified a number of triggers that are involved, including genetic predisposition, viral infections, and environmental factors. “Having an immediate family member with type 1 diabetes means your chances of developing the condition are 1 in 20, which is 15 times higher than the general population,” says Anastasia Albanese-O’Neill, Ph.D., associate vice president of community screening and clinical trial education of Breakthrough T1D (formerly known as JDRF), a global type 1 diabetes research and advocacy nonprofit.
Though type 1 diabetes has traditionally been seen as a disease predominantly affecting children and adolescents, recent research has shown otherwise. A recent study published in the Annals of Internal Medicine found that a significant proportion of individuals with type 1 were older than 30. “The median age of diagnosis for cases of type 1 diabetes is 24, with half being diagnosed after age 24,” explains study author Michael Fang, Ph.D, assistant professor in the Department of Epidemiology at Johns Hopkins Bloomberg School of Public Health.
Symptoms of type 1 diabetes can include frequent urination, excessive thirst, weakness, fatigue, and unexpected weight loss. However, some adults with type 1 may not initially show any signs of the condition. People with type 1 diabetes need to take insulin for the rest of their lives.
Type 2 Diabetes
Type 2 diabetes is the most common form of the disease, accounting for 90-95 percent of all cases (about 1 in 10 U.S. adults). With type 2 diabetes, your pancreas either doesn’t make enough insulin, or your body doesn’t use insulin effectively (which is known as insulin resistance), resulting in high blood sugar levels. As a result, it takes more insulin than normal to transport blood sugar into cells.
To compensate for insulin resistance, the pancreas produces more and more insulin in an attempt to keep blood sugar within a normal range. However, as insulin resistance worsens, the pancreas may eventually lose the ability to keep up with the increased demand. Scientists are still studying the precise mechanisms behind insulin resistance, which can be temporary or chronic, but excess body fat, especially around the belly, and physical inactivity often lead to it.
Being overweight is a significant risk factor for type 2 diabetes. A 2020 University of Copenhagen study found that individuals living with obesity were eight times more likely to develop type 2 diabetes than those who were at a healthier weight. The authors conclude: “Having normal body weight is crucial in preventing type 2 diabetes, regardless of genetic predisposition.”
While obesity is a key risk factor for type 2 diabetes, it isn’t the sole determinant. A significant number of people diagnosed with type 2 diabetes are at a normal weight, though exact figures are difficult to pin down and can vary across populations. Diabetes researcher Robert Lustig, M.D., Emeritus Professor of Pediatrics in the Division of Endocrinology at the University of California, San Francisco, suggests it could be as high as 25 percent. “Being overweight or obese is a good reason to be tested for type 2 diabetes,” he says. “But being thin is no excuse for ignoring your risk.”
Additionally, the CDC reports that certain racial and ethnic groups, such as American Indians, Alaska Natives, African Americans, and Hispanics, are more susceptible to adult-onset type 2 diabetes. “It’s an age-old question why,” says Neal D. Barnard, M.D., adjunct professor of medicine at George Washington University School of Medicine and Health Sciences. “Although some have suggested that genes, [a lower income] and limited access to affordable, nutritious foods are a couple of the risk factors that elevate the risk of diabetes.”
Age can also increase your risk of developing type 2 diabetes. An estimated 14 percent of Americans aged 45-64 (about 11 million people) have been diagnosed with type 2 diabetes, The prevalence increases among those aged 65 and older. According to the Mayo Clinic, some of the reasons for this spike in older individuals can be insulin resistance, usually as a result of obesity and inactivity; reduced insulin production from the pancreas; and loss of muscle mass.
However, experts note that type 2 diabetes is increasing in teens and young adults in the U.S. “This is due to rising rates of childhood and adolescent obesity,” says Judith Goldberg-Berman, M.D., Ph.D., a Greenwich, CT endocrinologist. “Factors that contribute to this are diets that are higher in processed foods and sugary beverages, lower in fruits and vegetables, and more sedentary lifestyles,” she says.
Gestational Diabetes
Gestational diabetes is a type of diabetes that develops in pregnancy when blood sugar levels become too high. This form of diabetes typically occurs in women who haven’t had diabetes before pregnancy. You’re also at higher risk for gestational diabetes if you are overweight, have a family history of type 2 diabetes, or come from certain ethnic groups.
During pregnancy, more fat is stored in your body, you consume more calories, and you may exercise less. All this can make your blood sugar levels higher than normal. Additionally, your placenta makes several hormones during pregnancy that prevent the body from using insulin effectively. Because of this, glucose builds up in the blood instead of being absorbed by the body’s cells. As the placenta grows, it produces more hormones, and the risk of insulin resistance increases. When the pancreas can’t make enough insulin to overcome the effect of the placenta’s hormones, gestational diabetes results.
Gestational diabetes typically develops between the 24th and 28th weeks of pregnancy. The good news is that it usually resolves after you give birth. However, about 50 percent of women who had gestational diabetes have a higher risk of developing type 2 diabets later in life.
To prevent gestational diabetes, focus on eating a healthy diet, staying physically active, and avoiding excessive weight gain.
Prediabetes
Prediabetes occurs when your blood glucose levels are higher than normal, but not high enough to be classified as diabetes. “Think of it like a yellow traffic light,” says Dr. Goldberg-Berman.“It’s a clear warning that you need to prepare and slow down before entering more dangerous territory.”
According to the CDC, more than 1 in 3 American adults has prediabetes, yet 81 percent are unaware of it. Without noticeable symptoms, prediabetes often goes undetected until health problems, such as type 2 diabetes, develop.
While obesity significantly increases prediabetes risk, other factors include age, family history, ethnicity, and a sedentary lifestyle.
The good news is that a prediabetes diagnosis can often be reversed through lifestyle changes, such as regular physical activity, a healthy diet, and maintaining a normal body weight. “Even losing 5-10 percent of your body weight can be very helpful,” says Dr. Goldberg-Berman.
How Is Diabetes Diagnosed?
Diagnosing diabetes and prediabetes usually begins with one of three tests that your doctor may order during a routine physical exam. However, it’s best not to assume your doctor will do this automatically, so if you’re concerned about your risk, make sure you ask for them
These tests can be easily added if you have risk factors for diabetes or are experiencing symptoms that suggest you may have progressed from prediabetes to type 2 diabetes. Symptoms include increased thirst or hunger, frequent urination, fatigue, or blurred vision.
Hemoglobin A1C (A1C) test: This blood test shows your average blood sugar level over the past two to three months. It can be done as part of a routine doctor’s appointment and does not require fasting.
Results are typically reported as a percentage:
- Less than 5.7 percent: You don’t have diabetes
- 5.7 percent to 6.4 percent: Indicates prediabetes
- 6.4 percent or higher: Diabetes (type 2 diabetes or type 1 diabetes)
Fasting blood sugar test: Also known as a fasting plasma glucose (FPG) test, this test measures the glucose in your blood after fasting 8-12 hours. Healthcare providers often order this test if you show signs of diabetes. It is usually performed in a doctor’s office, lab, or hospital. Results are expressed in milligrams of sugar per deciliter (mg/dL) of blood. If you don’t have any of the symptoms for diabetes, and your test result is 126 ml/dL or higher your doctor may ask you to repeat the test to confirm results.
- 99 mg/dL or lower: A normal fasting blood sugar result
- 100-125 mg/dL: Indicates prediabetes
- 126 ml/dL or higher: Indicates diabetes.
Glucose tolerance test: Also called the oral glucose tolerance test (OGTT), this test assesses how well your body processes sugar. It’s particularly useful for diagnosing gestational diabetes but it can also screen for prediabetes and diabetes.The test is performed either in your doctor’s office, or in a lab, After drinking a specially formulated glucose solution, your blood glucose levels are checked at set intervals for up to three hours. Providers use the following ranges for the two-hour test:
- Under 140 milligrams per deciliter (mg/dL): Normal
- 140-199 mg/dL: Prediabetes
- At or over 200 mg/dL: Diabetes
Treating Diabetes
Lifestyle choices, including eating a healthy, well-balanced diet, exercising, and staying at a healthy weight are key to managing type 2 diabetes.
Diet plays a vital role in preventing the progression of prediabetes to diabetes. “It’s surprising to think that the fat in cheese, meat, or fried foods could be leading us toward diabetes,” says Dr.Barnard.“But the good news is that when we set these foods aside, type 2 diabetes can improve and sometimes even go away.”
For smart meal planning, the American Diabetes Association (ADA) recommends following its Diabetes Plate tool. “This balanced approach to eating can help manage blood sugar levels and promote overall health,” says Stacey Krawczyk, a registered dietician and ADA’s director of nutrition and wellness.
The ADA’s Diabetes Plate protocol suggests:
- Filling half of a nine-inch plate with non-starchy vegetables (such as broccoli, carrots, or leafy greens)
- A quarter of the plate with lean protein (like grilled chicken, fish, or tofu)
- Another quarter with carbohydrates (preferably whole grains like brown rice or quinoa)
Additionally, incorporating healthy fats in moderation from sources like avocados, nuts, or olive oil is also recommended.
Physical activity is a crucial component of managing prediabetes and diabetes. Both resistance and aerobic exercises improve insulin sensitivity and help control blood sugar levels. Even daily life activities like walking, gardening, and housework can be beneficial. The key is to start slowly and gradually increase activity level over time.
Although lifestyle choices play a major role in managing type 2 diabetes, you may also need medication to keep your blood sugar at a healthy level.
There are no current oral medications for type 1 diabetes, as insulin can only currently be administered via injection or intravenously
Several classes of type 2 diabetic medicines exist, with each medicine working in a different way to lower blood glucose. Sometimes one medicine is enough. In some cases, however, combining two or three kinds can be more effective.
Oral Medications for Type 2 Diabetes
Metformin (e.g., brand names Fortamet, Glumetza) is the most common oral medication prescribed for diabetes. It is recommended by most experts as a first-line therapy. Metformin usually is taken two times a day.
- Benefits: Metformin is well-tolerated by most people. It works to keep blood sugar controlled, and helps your body use insulin effectively. Additionally, it is typically affordable, making it accessible when many prescription drugs have become prohibitively expensive.
- Side Effects: Nausea and diarrhea occur in up to 30 percent of patients when first starting the medication. It is not recommended for individuals with reduced kidney function. Under certain conditions, too much metformin can cause a rare but serious condition called lactic acidosis (too much acid builds in the blood).
Alpha-glucosidase inhibitors (e.g., Precose) are a class of medications that slow the digestion of carbohydrates, effectively reducing post-meal blood sugar spikes. They are taken three times daily with the first bite of each main meal.
- Benefits: Improved blood glucose control with a low risk of hypoglycemia or weight gain. The drugs can be used alone or combined with other pills.
- Side Effects: They can cause gas and diarrhea during the first few weeks of taking the medication.
Dipeptidyl peptidase-4 (DPP-4) inhibitors (e.g., Januvia) help your body produce more insulin when your blood sugar is rising. This medication is usually taken once a day, either before or after meals.
- Benefits: These medications help improve A1C without causing hypoglycemia. They prevent the breakdown of naturally occurring hormones that reduce blood glucose levels in the body.
- Side Effects: Infections of the upper respiratory or urinary tract, headaches, and can increase the risk of hypoglycemia, pancreatitis, and acute renal failure. In 2015, the FDA issued a safety announcement warning that DPP-4 inhibitors may cause severe joint pain. Patients should contact their healthcare professional right away if they experience severe and persistent joint pain.
Meglitinides (e.g., Starlix) trigger rapid, short-term insulin release.
- Benefits: These medications work quickly and are particularly helpful for people with varying meal schedules or who need to control post-meal blood sugar spikes. While brand name meglitinides like Prandin and Starlix have been discontinued, generic medications are still available. They are taken before each meal to help lower glucose after you eat.
- Side Effects: Because meglitinides stimulate the release of insulin, blood sugar levels may drop too low and cause hypoglycemia. Weight gain is also a possible side effect.
SGLT2 Inhibitors (e.g., Jardiance, Invokana) are a newer class of medications that help the kidneys to remove excess sugar from the body through urine. SGLT Inhibitors are usually taken once a day, before the first meal of the day, with or without food.
- Benefits: By increasing the amount of glucose excreted in the urine, they can lower your blood sugar and lead to modest weight loss in many people. SGLT2 inhibitors also have cardiovascular benefits and have been shown to slow the progression of diabetic kidney disease. The drugs may be prescribed for patients with type 2 diabetes who do not want to start insulin.
- Side Effects: They cause the kidneys to excrete more sugar in urine, increasing the risk of genital yeast and urinary tract infections. Nausea and constipation are also possible side effects.
Sulfonylureas (e.g., Glucotrol XL) stimulate the pancreas to produce more insulin. They have been extensively used for treatment of type 2 diabetes for more than 50 years. They are generally taken 30 minutes before meals.
- Benefits: These drugs are relatively inexpensive compared to newer diabetes medications and are often chosen as a second-line treatment after metformin due to their effectiveness and low cost.
- Side Effects: All sulfonylurea drugs have similar effects on blood sugar levels, but they differ in side effects and interactions with other drugs. Because they stimulate insulin production, blood sugar levels may drop too low, which can cause hypoglycemia. Weight gain is another common side effect. Additional infrequent side effects may include nausea, dizziness, or headache.
Thiazolidinediones (e.g., Actos) are long-lasting medications for type 2 diabetes that help muscle and fat tissues be more sensitive to insulin. They can be taken once-daily, either in the morning or in the evening.
- Benefits: These drugs improve blood glucose control. They may be prescribed for patients with significant insulin resistance or those who need sustained blood sugar control.
- Side Effects: There are several undesirable side effects, particularly with long term use. May cause fluid retention, weight gain, and increase the risk of anemia (low red blood cell counts) and heart failure.
Injectable Medications
There are many types of injectable diabetes medications, including insulin and other medications that change the way your body uses insulin.
Insulin is crucial for managing blood glucose levels, particularly for individuals with type 1 diabetes and some with advanced type 2 diabetes. Various types of insulin are available, which differ in onset, duration, and chemical structure. People with type 1 diabes inject insulin every day, often up to 4 times a day.
- Benefits: Insulin lowers and controls blood glucose levels, reducing the risk of long-term diabetes complications.
- Side Effects: The primary concern is hypoglycemia, which can cause sweating, confusion, and in severe cases, loss of consciousness. Insulin can also promote weight gain, especially when starting therapy.
Dopamine-2 agonists (e.g.,Cycloset) influence brain areas that regulate hormone release, metabolism, and sleep-wake cycles. For type 2 diabetes, this medication is taken once a day within two hours after waking up in the morning.
- Benefits: Bromocriptine, (whose brand name is Cycloset) is the only dopamine 2 agonist approved to treat type 2 diabetes. It works by reversing insulin resistance and reducing glucose production in the liver. It can help control blood sugar levels when other diabetes medications are not sufficiently effective. Offers an alternative treatment option for patients struggling with standard therapies.
- Side Effects: Common side effects include nausea, dizziness, and fatigue. Rare but severe side effects can include heart problems and risk of psychosis, particularly in people with a history of mental health disorders.
GLP-1 Receptor Agonists (e.g., Ozempic) enhance the body’s insulin effectiveness in people with type 2 diabetes. These drugs, including heavily advertised brands like Ozempic (semaglutide) and Trulicity (dulaglutide), mimic the GLP-1 hormone naturally released in the gastrointestinal tract. Injections are given once daily or weekly depending on the medication.
- Benefits: GLP-1 agonists reduce post-meal blood sugar spikes, decrease liver glucose production, and slow stomach emptying, promoting a feeling of fullness. Additionally, they lower cardiovascular disease risk in high-risk individuals, promote weight loss, and improve blood glucose levels.
- Side Effects: According to recent research, as many as 1 in 20 new users of GLP-1s who are living with obesity or who have diabetes develop stomach paralysis. This is a disorder affecting your stomach nerves and muscles that leads to food sitting too long in your stomach. Other common side effects include nausea, vomiting, and diarrhea, which are typically mild to moderate and often subside over time. There is also a rare potential for pancreatitis.
GIP/GLP-1 Agonists (e.g., Mounjaro), are a class of dual-action medications used with diet and exercise to lower blood sugar levels in adults with type 2 diabetes. These medications are also popular as off-label weight loss aids. Mounjaro is currently the only FDA-approved GIP/GLP-1 receptor agonist on the market for type 2 diabetes and is injected once a week, with or without food.
- Benefits: A recent study published in JAMA Internal Medicine found that Mounjaro is more effective for weight loss and lowering hemoglobin A1C than Ozempic. It also has a low risk of hypoglycemia.
- Side Effects: Like GLP-1 receptor analysts, nausea and vomiting are common side effects when starting or increasing dosages. Although serious side effects are rare, they include pancreatitis and allergic reactions, including swelling of the lips, tongue, face or throat, difficulty breathing or swallowing, rash and itching.
Diabetes remains a critical public health issue, affecting millions. Left untreated, it can lead to serious, even life-threatening complications. Key priorities include increasing awareness about prevention and treatment, and identifying undiagnosed cases. While current management strategies are essential, research offers hope for more effective approaches in the future, with the potential to significantly improve millions of lives.
