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What are the symptoms and signs of diabetes?

Type 1 diabetes

Type 1 diabetes often develops suddenly and can produce symptoms such as:

  • Abnormal thirst and a dry mouth
  • Frequent urination
  • Lack of energy and extreme tiredness
  • Constant hunger
  • Sudden weight loss
  • Blurred vision

Type 1 diabetes is diagnosed by an elevated blood glucose level in the presence of some these symptoms.

Type 2 diabetes

The symptoms* of type 2 diabetes include:

  • Frequent urination
  • Excessive thirst
  • Extreme hunger
  • Blurred vision
  • Lack of energy and extreme tiredness

Many people with type 2 diabetes remain unaware of their condition for a long time, because the symptoms are usually not as obvious as those in type 1 diabetes and may take years to be recognized.

How is diabetes diagnosed?

There are several ways to diagnose diabetes. You may be tested twice, on 2 different days. Sometimes, if your blood sugar levels are very high, your doctor may only test once to tell if you have diabetes.

Here are the common blood tests§ used to tell if you have diabetes:

  • A1C test: Measures your blood sugar for the past 2-3 months. With this test, you don't have to fast or drink anything special.
  • Fasting Plasma Glucose (FPG) test: Checks what is called your "fasting glucose levels." For this, you can’t eat or drink anything except water for 8 hours before the test. The test is usually scheduled early in the day, before breakfast.
  • Oral Glucose Tolerance Test (OGTT): Tests how your body responds to a glucose challenge. For this test, you drink a special sweet drink. Your blood sugar levels are tested before and after the drink.
  • Random (also called Casual) Plasma Glucose Test: When the doctor checks your blood any time, without any preparation for the test. This is usually done when you have obvious diabetes symptoms like losing weight suddenly, feeling very thirsty, and/or needing to urinate all the time.

*IDF Diabetes Atlas (7th Ed.) (2015). Brussels, Belgium: International Diabetes Federation.

§ American Diabetes Association: Alexandria, VA; c1995-2016. Accessed June 14, 2017 @