What Is Impaired Fasting Glucose?

What Is Impaired Fasting Glucose?

What Is Fasting Plasma Glucose?

Fasting plasma glucose (FPG) refers to blood glucose levels measured after a defined period of fasting.1 Average FPG usually ranges between 80-90 mg/dL, meaning 80-90 milligram (ie, milligram is 1/1000 gram) of glucose present in a deciliter (ie, deciliter is 1/10 liter) of blood.2 Measuring FPG levels is one of the diagnostic tests for diabetes.1


How Is Fasting Glucose Measured?  

To measure FPG levels for the purpose of diagnosing diabetes, 8 hours of fasting (ie, no caloric intake) is required.1 After fasting, a health care professional will draw blood from a vein, from which blood glucose levels will be measured.3 Glucometers and continuous glucose monitors should not be used for diagnostic purposes.


What Is Impaired Fasting Glucose?  

Impaired fasting glucose (IFG) in a diagnostic sense is defined as elevated FPG levels measuring between 100 mg/dL to 125 mg/dL.1 IFG is one of the ways to diagnose prediabetes. Prediabetes does not meet the diagnostic criteria for diabetes but has glucose levels too high to be considered normal and is considered a risk factor for type 2 diabetes mellitus and cardiovascular disease. When IFG worsens and FPG measures above 125 mg/dL, diabetes is diagnosed.

Beyond the numbers, IFG signifies that the body experiences hyperglycemia (ie, high blood glucose levels) even in the absence of caloric consumption, when blood glucose levels should be low.4 Studies indicate that IFG is attributed to the decline in pancreatic b-cell function (responsible for insulin secretion), reduced insulin sensitivity of the liver (reduced responsiveness to insulin to take up glucose), and inappropriately elevated glucagon secretion (a hormone that signals that glucose should be synthesized).

1. American Diabetes Association Professional Practice Committee.
2. Diagnosis and Classification of Diabetes: Standards of Care in Diabetes—2024. Diabetes Care. 2023;47(Supplement_1):S20-S42. doi:10.2337/dc24-S002 2. Nakrani MN, Wineland RH, Anjum F. Physiology, Glucose Metabolism. In: StatPearls. StatPearls Publishing; 2024. Accessed February 26, 2024. http://www.ncbi.nlm.nih.gov/books/NBK560599/
3. Pippitt K, Li M, Gurgle HE. Diabetes Mellitus: Screening and Diagnosis. Am Fam Physician. 2016;93(2):103-109.
4. Færch K, Borch-Johnsen K, Holst JJ, Vaag A. Pathophysiology and Aetiology of Impaired Fasting Glycaemia and Impaired Glucose Tolerance: Does It Matter for Prevention and Treatment of Type 2 Diabetes? Diabetologia. 2009;52(9):1714-1723. doi:10.1007/s00125-009-1443-3



The content of this article is intended to provide a general information and knowledge on the subject matter. The views expressed in newsletters, articles, and blogs in the i-SENS USA website are not necessarily those of i-SENS Incorporated, i-SENS USA Incorporated or our publishers. Medical or nutritional information on i-SENS USA website is not intended to replace professional medical advice – you should always consult a specialist with any questions about your specific circumstances.

Add a comment