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Overview of Diabetes Mellitus

What is diabetes mellitus?

Diabetes occurs when your body does not make enough insulin. Or when your body can't use the insulin that's made. Diabetes is called a metabolic disorder because the disease affects the way the body uses food to make blood sugar (glucose). Glucose is the body's main fuel source. The 3 main types of diabetes are:

  • Type 1 diabetes. Type 1 diabetes is an autoimmune disease. It occurs when your immune system attacks the pancreas that make insulin. This leads to no insulin, or a low amount of insulin in the body. People with type 1 diabetes must take insulin every day and check their blood sugars often

  • Type 2 diabetes. Type 2 diabetes occurs because the body can't make enough insulin. Or because your body can't correctly use insulin. This is called insulin resistance. Type 2 diabetes may be controlled with diet, exercise, and weight loss. You may need to take medicine by mouth (oral) or as a shot.

  • Gestational diabetes. This is diabetes that occurs during pregnancy. Blood sugar is high, and other symptoms of diabetes occur. In many cases, gestational diabetes goes away after the baby is born. But it increases the risk for type 2 diabetes later in life.

What is prediabetes?

Prediabetes often occurs before type 2 diabetes. In prediabetes, blood glucose levels are higher than normal, but not high enough to be diagnosed as type 2 diabetes. Prediabetes also increases the risk for type 2 diabetes, heart disease, and stroke. You may be able to delay or prevent type 2 diabetes by making lifestyle changes. These include losing weight if you are overweight and getting more exercise.

How does diabetes affect blood sugar?

Insulin is a hormone. It's made in the pancreas. Your body needs insulin to move blood sugar (glucose) into the cells. Normally insulin is in the body, ready to move the glucose. But when you have diabetes, the pancreas makes too little or no insulin. Or certain cells in the body don't respond to the insulin that is made. This causes glucose to build up in the blood. The extra glucose passes into the urine and out of the body. Your body is left without its main source of fuel.

What is maturity-onset diabetes in the young (MODY)?

Maturity-onset diabetes of the young (MODY) is a group of different types of inherited diabetes. They occur in teens and young adults. MODY is often at first incorrectly diagnosed as type 1 or type 2 diabetes.

The symptoms of diabetes linked to MODY vary. It depends on the type of MODY diagnosed. MODY 2 seems to be the mildest form of the disease. It often causes only mild high blood sugar (hyperglycemia). It also affects how the body responds to blood sugar. The other forms of MODY may need treatment with insulin, much like type 1 diabetes. Family members of people with MODY are at much greater risk for the condition. Your healthcare provider may diagnose MODY if 3 generations of your family have been diagnosed with mild diabetes before age 25. It's also more likely if your family members are not obese and are not resistant to insulin. 

Online Medical Reviewer: Raymond Kent Turley BSN MSN RN
Online Medical Reviewer: Rita Sather RN
Online Medical Reviewer: Robert Hurd MD
Date Last Reviewed: 6/1/2022
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