Prediabetes Diagnosis

Submitted by Thiruvelan on Wed, 10/09/2013
Prediabetes Diagnosis

A prediabetes diagnosis is by using blood sugar tests. If your number is higher than most non-obese healthy individuals, then you are diagnosed as prediabetes. 

Prediabetes Screening Guidelines 

Prediabetes also called borderline diabetes, impaired glucose tolerance (IGT), or impaired fasting glucose (IFG) depending on which test was used to diagnose it.

Who may have prediabetes? 

A standard for prediabetes screening based on certain diabetes risk factors. Those who are over 40 years and overweight, specifically large waist size should be screened for abnormal blood glucose every three years.

Reference: Final Recommendation Statement: Abnormal Blood Glucose and Type 2 Diabetes Mellitus: Screening. U.S. Preventive Services Task Force. November 2016.

How is prediabetes diagnosed?

Blood tests are used to diagnose pre-diabetes. They are fasting blood glucose test, oral glucose tolerance test, and glycated hemoglobin A1C test. 

Prediabetes test - How can I get tested for prediabetes?

Clinical guidelines have defined prediabetes range as below:

  1. Impaired fasting glucose (IFG) - fasting plasma glucose [FPG] of 100 to 125 mg/dL (or 5.5 to 6.9 mmol/L). Fasting Plasma Glucose (FPG) is a blood-glucose test taken after not having anything to eat or drink (except water - even do not drink a lot of water before the test) for a minimum of eight hours before the test. This test is conveniently carried out in the morning, before breakfast.
  2. Impaired glucose tolerance (IGT) - 2-hour oral glucose tolerance test [OGTT] of 140 to 199 mg/dl (or 7.8 to 11 mmol/L). Oral glucose tolerance test (OGTT) or glucose challenge test is a blood-glucose two hours after you eat a carbohydrate-rich food or drink a special sweet drink.
  3. Prediabetes A1C - The ADA updated its recommendation. They added A1C for prediabetes diagnosis; the diagnosis range is from 5.7 to 6.4%. A1C is a test done at any time, there is no fast or drink anything, and it measures the average BS for the past two to three months.

Reference: American Diabetes Association. Standards of medical care in diabetes—2010. Diabetes Care 2010; 33: S11– S61

What is the normal healthy blood glucose range?

Normal blood-glucose levels noted among most young, healthy persons (non-diabetic adults) are as below:

  • Fasting blood glucose level: 70–90 mg/dl (3.89–5.00 mmol/l)
  • One hour after a meal: 90–125 mg/dl (5.00–6.94 mmol/l)
  • Two hours after a meal: 90–110 mg/dl (5.00–6.11 mmol/l)
  • Five hours after a meal: 70–90 mg/dl (3.89–5.00 mmol/l)

Prediabetes level - If your blood glucose levels are more than the above-said range, then you are at increased risk towards prediabetes.

What is Impaired Fasting Glucose (IFG) & Impaired Glucose Tolerance (IGT)?

Both IFG & IGT are insulin-resistance. People with IFG along have hepatic insulin resistance and optimal muscle insulin sensitivity. People with IGT alone have been reasonable to slightly reduced hepatic insulin sensitivity and moderate to severe muscle insulin resistance. 

People with both IFG & IGT possess both muscle and hepatic insulin resistance; they have about double the chances to develop diabetes than people with just one of them.

What test is preferable in early prediabetes diagnosis?

A study shows the higher sensitivity of IGT over IFG for predicting progression to type2 diabetes. 

A study "Impaired fasting glucose or impaired glucose tolerance, what best predicts future diabetes in Mauritius," was published in Diabetes Care March 1999 vol. 22 no. 3 399-402. Screening by the criteria for IFG alone would identify fewer people who subsequently, progress to type2 diabetes than would be the oral glucose tolerance test.

Numerous studies show both IFG & IGT has an association with a modestly increased risk towards CVD, with IGT being a slightly stronger risk predictor. Intensive lifestyle changes can help delay or prevent diabetes and risk factors for CVD.

Thus, it is always preferable to take both IFG & IGT (is particularly essential) on the same day or alternate day to predict prediabetes in the early stage. 

Unhealthy BS numbers

Change your lifestyle when your numbers are in an unhealthy range. The actual healthy blood-glucose numbers are as below:  

  • Fasting blood glucose level over 90 mg/dl (or 5.00 mmol/l)
  • One hour after meal level over 125 mg/dl (or 6.94 mmol/l)
  • Two hours after meal level over 110 mg/dl (or 6.11 mmol/l)
  • Five hours after meal level over 90 mg/dl (or 5.00 mmol/l)

If your blood-glucose number is in the unhealthy range, then this is an alarm towards prediabetes. Take the necessary steps to prevent its progression as well as stop diabetes complications.

The early intervention help delays the onset of diabetes and reverses prediabetes. Additionally, preserving beta-cell function and improving insulin sensitivity can prevent the likelihood of microvascular and cardiovascular complications.