Early Signs You Have Diabetes

Medically Reviewed by Dr. K on 19 May 2022

Table of Contents


  1. Diagnostic Tests for Diabetes
  2. How Are Diabetes and Prediabetes Diagnosed?
  3. Fasting Plasma Glucose (FPG) Test
  4. Oral Glucose Tolerance Test (OGTT)
  5. Random Plasma Glucose Test


Diagnostic Tests for Diabetes

Diabetes is diagnosed by the following tests:


  • Fasting plasma glucose test: A fasting plasma glucose test For at least 8 hours without food, the glucose metre tests the blood glucose. This test is used to determine if a person has diabetes or prediabetes.

  • Oral glucose tolerance test: For at least eight hours without food for two hours after drinking a glucose-containing drink, the glucose metre tests your blood sugar. This test can be used to determine whether a person has diabetes or prediabetes.

  • Random plasma glucose test: Your doctor will monitor your blood sugar regardless of what you last ate. This procedure, along with an assessment of symptoms, is used to diagnose diabetes, but not prediabetes.

  • Haemoglobin A1c (HbA1c) test: can be conducted without fasting and is helpful for diagnosing and confirming prediabetes or diabetes.

Positive test findings can be validated on a separate day by repeating the fasting plasma glucose or oral glucose tolerance test. Your doctor may prescribe a zinc transporter 8 autoantibody (ZnT8Ab) test when you are first diagnosed with diabetes. Along with other information and test results, this blood test will assist in determining if an individual has type 1 diabetes and not another type. The aim of the ZnT8Ab test is to provide a rapid and reliable diagnosis that can result in appropriate care.

Fasting Plasma Glucose (FPG) Test

When performed in the morning, the FPG is most accurate. If your fasting glucose level is between 100 and 125 mg/dL, you have impaired fasting glucose (IFG), a form of prediabetes in which you are more prone to develop type 2 diabetes but do not yet have it. A blood sugar level of 126 mg/dL or greater, as validated by repeated the examination on another day, indicates diabetes.

Oral Glucose Tolerance Test (OGTT)

The OGTT is more sensitive than the FPG test for diagnosing prediabetes, according to research, but it is more challenging to administer. Before taking the OGTT, you must fast for at least eight hours. Immediately before and two hours after drinking a substance containing 75 grams of glucose absorbed in water, your plasma (blood) glucose is then measured. If your blood sugar level is between 140 and 199 mg/dL two hours after swallowing the liquid, you have reduced glucose tolerance, or IGT, a form of prediabetes that means you are more prone to develop type 2 diabetes but do not yet have it. Diabetes is diagnosed by a two-hour glucose level of 200 mg/dL or more, which may be verified by administering the examination for another day.

Plasma glucose levels determined during the OGTT may also be used to detect gestational diabetes. During the procedure, blood sugar levels are tested four times. You have gestational diabetes if the blood sugar levels are higher than average at least twice during the exam. 

Random Plasma Glucose Test

Diabetes can be diagnosed by a random blood glucose level of 200 mg/dL or more, as well as the occurrence of the following symptoms:

  • Increased urination
  • Increased thirst
  • Unexplained weight loss

Fatigue, poor vision, increased thirst, and unhealed sores are among the other symptoms. To confirm the diagnosis of diabetes, the doctor can use the FPG or the OGTT to monitor the blood glucose level on another day.

Hemoglobin A1c is also used as a monitoring aid or diagnostic procedure for prediabetes and diabetes in newer guidelines (the test is normally used to measure blood glucose control in diabetes patients over several months). Prediabetes is described as a HbA1c level of 5.7% to 6.4%, which can be reversed through lifestyle adjustments. Diabetes is diagnosed when the HbA1c level is 6.5% or above.


Referenced on  15/4/2021

  1. About diabetes. (n.d.).
  2. Delahanty LM. (2018). Patient education: Type 2 diabetes and diet (Beyond the basics).
  3. Diabetes. (2018).
  4. Diabetes prevention program (DPP). (n.d.).
  5. Diabetes symptoms. (2018).
  6. Insulin, medicines, & other diabetes treatments. (2016). 
  7. Mayo Clinic Staff. (2018). Diabetes: Symptoms & causes.
  8. Mayo Clinic Staff. (2017). Type 1 diabetes: Symptoms & causes.
  9. Mayo Clinic Staff. (2018). Type 2 diabetes: Diagnosis & treatment.
  10. Mayo Clinic Staff. (2017). Type 2 diabetes in children.
  11. Prediabetes: Your chance to prevent type 2 diabetes. (2018).
  12. Symptoms and causes of diabetes. (2016).
  13. Type 1 diabetes nutrition. (n.d.).
  14. What are my options? (2015).
  15. What is diabetes? (2016).
  16. What is type 1 diabetes? (2017).
  17. Who’s at risk? (2017).
  18. https://www.webmd.com/diabetes/guide/diagnosis-diabetes

Previous Post

Brain Cancer Treatment

Next Post

Diabetes Insipidus: Types, Symptoms, Causes, Risk Factors, Diagnosis, Complications, Treatments, Outlook

Related Posts