What Is Type 2 Diabetes?

Type 2 diabetes is a progressive, chronic disease that prevents a person's body from properly using glucose (sugar). People with type 2 diabetes usually have insulin resistance and metabolic syndrome.

In type 2 diabetes, the cells become resistant to insulin, which is a hormone created by the pancreas that controls the amount of glucose in your bloodstream. As a result, the pancreas makes more insulin. Over time, the pancreas cannot produce enough insulin to keep blood sugars in a healthy range.

This article discusses the differences between type 1 and type 2 diabetes, as well as the symptoms, diagnosis, and treatment of type 2 diabetes.

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Type 1 vs. Type 2 Diabetes: What It Means to Have Type 2

Type 1 and type 2 diabetes are both disorders in glucose metabolism. However, their clinical presentation and progression are different. It's important to differentiate between the two conditions since treatment plans differ.

Type 1 diabetes is an autoimmune disease. It occurs when the body mistakenly attacks the pancreas's insulin-making cells (beta cells). People with type 1 diabetes make little to no insulin and must take it via injection or infusion to live. Type 1 diabetes used to be called juvenile diabetes because it was more likely to be diagnosed in childhood. But it can also develop later in life.

Type 2 diabetes accounts for 90% to 95% of all diabetes cases. It is often referred to as a lifestyle disease because your weight, age, smoking, diet, and lack of exercise can increase your risk. People of certain racial and ethnic populations have a higher incidence of the disease, as well.

In addition, people who develop type 2 diabetes are more likely to have a cluster of factors, including high cholesterol, high blood pressure, high triglycerides, and abdominal adiposity (excess fat in the abdomen).

Type 2 Diabetes Symptoms

Type 2 diabetes develops gradually. Often, people do not have noticeable symptoms, especially in the earlier stages (prediabetes). As the disease progresses, you may experience:

What Causes Type 2 Diabetes?

Type 2 diabetes occurs when glucose (sugar) cannot enter the cells and stays in the bloodstream above normal levels. A defect in insulin secretion, insulin resistance, or a combination of both causes this. Certain contributing factors to the disease include:

  • Age: Diabetes occurs more frequently in people over 45.
  • Weight: You are considered overweight or obese if you have a body mass index (BMI) greater than 25 kilograms per meters squared (kg/m2) for most Americans (greater than or equal to 23 kg/m2 for Asian Americans), or have waist circumference greater than 40 inches in men or greater than 35 inches in women.
  • Lack of exercise: This generally is defined as less than three days a week of physical activity.
  • Other conditions: These include having prediabetes or having had a gestational diabetes diagnosis, atherosclerotic cardiovascular disease, metabolic syndrome, nonalcoholic fatty liver disease (NAFLD), or polycystic ovary syndrome (PCOS).
  • Race: Type 2 diabetes is more common among certain racial and ethnic populations, including African American, Native American, Latinx, and Asian American people.
  • Genetic predisposition: The lifetime risk of developing type 2 diabetes is 3 times higher in those who have a first-degree relative with the disease.
  • Certain medications: Treatment with atypical antipsychotics, human immunodeficiency virus (HIV) medications, or glucocorticoids.

Is Type 2 Diabetes Genetic?

There is a genetic component to developing type 2 diabetes. However, genetics is complicated, and there is much to investigate and discover. Some genes connected to diabetes are related to insulin resistance, and others to beta cell function. Research shows a wide range of heritability of type 2 diabetes, ranging from 20% to 80%.

Type 2 Diabetes Diagnosis

There are several ways to diagnose type 2 diabetes, including with blood tests and blood draws during an oral glucose tolerance test (a test in which you drink a sugary drink and evaluate how your body responds to the sugar). Your healthcare provider may decide to do a random blood sugar test. A random blood sugar reading greater than or equal to 200 milligrams per deciliter (mg/dL) qualifies for a diabetes diagnosis.

When you do not have classic symptoms, diagnosis requires two abnormal test results from the same or different sample. This includes fasting plasma glucose (FPG), two-hour plasma (blood) value from an oral glucose tolerance test or hemoglobin A1C.

Type 2 Diabetes Treatment

Treatment for type 2 diabetes includes lifestyle changes, eating a nutritious diet, exercise, weight loss (when indicated), adequate sleep, and stress reduction. You can be prescribed oral, insulin, or non-insulin injectable medications to control blood sugar. Medications should always be used in conjunction with lifestyle changes, including changes to diet and exercise.

Receiving diabetes self-management education is important to help lower your risk of diabetes complications and decrease costs. It reduces or eliminates medications and emergency room visits and allows you access to cost-saving programs.

Can Type 2 Diabetes Be Reversed?

Research shows that intensive lifestyle interventions, including changes in diet, exercise, and weight loss, can put diabetes into remission. There is a greater chance of this happening in people who have had diabetes for a shorter duration of time and those who can still make adequate amounts of insulin.

Type 2 Diabetes Diet: Foods to Eat and Avoid

There is no one-size-fits-all diet for diabetes. And while certain foods can increase blood sugars more quickly than others, there are no forbidden foods. Instead, you will benefit from a modified carbohydrate diet. Carbohydrates found in fruit, dairy, grains, starchy vegetables, legumes, snack foods, and desserts impact blood sugars the most.

Research suggests that people who eat more plants or follow a Mediterranean diet experience many health benefits, including a reduced risk of diabetes. This food plan contains various high-fiber foods, such as vegetables, fruits, nuts, seeds, beans, and whole grains. Foods higher in fiber have a more favorable effect on blood sugar because it is digested slowly, reducing large blood sugar spikes.

Aim for a well-balanced meal, especially concerning the amount of food and the types of carbohydrates you eat. A general rule of thumb is to limit carbohydrates to a portion about the size of your fist, which is equivalent to 1 cup of cooked grain. Fill up half your plate with vegetables, and always add lean protein to each meal.

Mediterranean Style of Eating

In a meta-analysis of 17 studies, the Mediterranean diet improved fasting glucose and A1C levels for those with type 2 diabetes.

To manage inflammation, a key factor in diabetes, choose foods that are lower in saturated and trans fats and higher in heart-healthy fats, such as:

  • Fatty fish like salmon
  • Walnuts
  • Flax
  • Chia seed
  • White meat chicken, turkey
  • Lean beef
  • Soy or soybean (tofu)
  • Tempeh

Reduce your intake of fried foods and cured meats like sausage, bacon, ham, and cold cuts. Bagels, white bread, and pasta can increase blood sugar quickly because they are high in carbohydrates and low in fiber. Large glucose fluctuations are associated with diabetes complications and cardiovascular disease. More research is needed to determine the exact effects.

Meeting with a registered dietitian who can help you maintain the pleasure of eating is important. They can teach you how to make some simple changes to your diet.

How to Check Blood Sugar

The number of times you should check your blood sugar depends on your glycemic control and medication regimen. If you take medications such as insulin, you are at increased risk of developing hypoglycemia (low blood sugar) and may need to check your numbers more frequently. It's also important to regularly check your blood sugar if you've started a new medication, made changes to your diet or exercise regimen, and want to reduce your intake of medicines.

A healthcare provider will tell you when and how to test using a glucometer. A continuous glucose monitor may be more appropriate for people who take specific medications, have had diabetes for a long time, or are at higher risk for low blood sugar.

Complications From Type 2 Diabetes

Chronically high blood sugar can cause microvascular and macrovascular complications. This means the small vessels, like those in the eyes, and larger ones, like those in the heart, can be affected.

Complications can impact nearly every body system and organ. Long-term complications include:

Complications of Untreated Type 2 Diabetes

Untreated complications occur when someone does not know they have diabetes. Damage to the eyes can happen before a diabetes diagnosis is made, so a dilated eye exam is necessary every year after.

Elevated blood sugar can also cause acute conditions, such as diabetic ketoacidosis (more common in people with type 1 diabetes) or hyperglycemic hyperosmolar nonketotic syndrome (more common in people with type 2 diabetes). Both conditions are emergencies and should be treated immediately.

Diabetes and Pregnancy: Gestational Diabetes

Gestational diabetes occurs during pregnancy and typically disappears once the baby is born. People with and without risk factors can develop gestational diabetes. Other risk factors include:

  • Genetics
  • Age
  • Weight
  • Ethnicity
  • Other health conditions
  • Previous pregnancy with gestational diabetes
  • Prediabetes
  • Changes in the body during pregnancy

Insulin resistance occurs in pregnancy during weeks 20 to 24. Gestational diabetes increases your chances of developing prediabetes and type 2 diabetes later in life. Screening after delivery and every three years after that will be necessary.

How to Prevent Type 2 Diabetes

Certain risk factors for type 2 diabetes, like genetics, are outside your control, but you can take steps to delay or prevent the development of type 2 diabetes. Make changes toward the modifiable factors, such as eating patterns and physical activity. Small, sustainable, and consistent changes are the longest lasting and impactful.


What you eat can significantly impact your blood sugars and overall health. Eating a variety of foods that are rich in color, such as fruits and vegetables, provides antioxidants that combat inflammation. Choosing carbohydrates rich in fiber is important for blood sugar control and is associated with a reduced risk of heart disease and diabetes.

Decrease added sugar in foods and beverages, which can significantly improve your blood glucose and promote warranted weight loss. Find healthier alternatives, such as sugar-free beverages or carbonated seltzer without added sugar. Use artificial sweeteners or sugar-free alternatives because these substances do not get digested or metabolized in the body.

Physical Activity

Exercise improves insulin sensitivity; it helps your body use the insulin you make more efficiently. Find an activity you love, start slowly, and build up gradually. If you are new to exercise, get clearance from a healthcare provider before starting.

Weight Loss

A small amount of weight loss (5% to 7%) in those that need to lose weight can significantly impact blood sugars. The scale doesn't have to be your only measurement tool. Another way to measure success is to assess your energy, how your clothes fit, or if you are getting better sleep.

Consult with your healthcare provider to develop the best weight loss management or program that fits your needs. Losing weight is encouraged for people with excess weight with chronic diseases. Following a weight management plan can help you stay on track with your nutrition and fitness goals.


Studies have shown that sleep problems can increase the risk of insulin resistance and prediabetes. Aim to get seven to nine hours of sleep per night. If your nightly patterns are way off, make gradual changes, such as going to bed 15 minutes earlier each night.

Other Factors

Having a healthy gut microbiome, reducing stress, and not smoking are all important factors in reducing inflammation.

Daily Management of Type 2 Diabetes

Daily management of type 2 diabetes requires making decisions about food, medicines, exercise, blood sugar testing, and more. You can live a healthy life with diabetes.

Whether you are newly diagnosed or have had diabetes for a long time, finding support and seeking education or further education regarding your condition will help you to manage your disease better. Contact your healthcare provider and insurance carrier to evaluate your options, such as meeting with a certified diabetes care and education specialist (CDCES).


Type 2 diabetes is a serious and chronic health condition that needs to be managed daily. People with diabetes are at increased risk of developing complications, especially if they have had it for a long time or it is poorly managed. But you can take steps to delay, prevent, and manage the disease. Your treatment plan will be unique to you and should take into consideration your age, weight, lifestyle, health history, culture, and economics.

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By Barbie Cervoni MS, RD, CDCES, CDN
Barbie Cervoni MS, RD, CDCES, CDN, is a registered dietitian and certified diabetes care and education specialist.