Lexicon
Fasting Glucose
Definition
Fasting plasma glucose is a measure of blood glucose concentration after an overnight fast and is one of the most frequently measured parameters for detecting intermediate hyperglycaemia and type 2 diabetes. [1] Impaired fasting glucose and impaired glucose tolerance are the two major phenotypes of prediabetes and may represent different pathophysiologies with differing natural history and risk of adverse outcomes. [1] Raised fasting glucose is one of the component risk factors of the metabolic syndrome, where three abnormal findings out of 5 qualify a person for the diagnosis. [2]
How it works
Type 2 diabetes involves progressive loss of insulin secretion from pancreatic beta cells in the setting of insulin resistance and manifests clinically as hyperglycemia, which fasting glucose captures. [3] Fasting glucose and HbA1c measure different things: HbA1c reflects average glycemia over months, whereas fasting glucose is a single-timepoint measure, and the two tests differ in sensitivity and specificity for detecting diabetes. [4]
Connected concepts
How it's measured
Fasting plasma glucose and HbA1c are the key dysglycemia screening tests, and the American Diabetes Association and US Preventive Services Task Force advise opportunistic 3-yearly screening in high-risk individuals. [5] Diagnosis of prediabetes and diabetes is based on glucose criteria measured by the fasting plasma glucose test and the oral glucose tolerance test. [6] Fasting glucose is assessed alongside fasting insulin as a complementary marker of glycemic control, and both decline together with insulin resistance in normoglycemic adults undergoing prolonged fasting [7]
What levels mean
Diabetes is diagnosed if fasting
Community knowledge
## Monitoring And Targets
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- 1.Unnikrishnan R, Shaw JE, Chan JCN, Wild SH, Peters AL, Orrange S, Roden M, Mohan V. Prediabetes. Nat Rev Dis Primers · 2025
- 2.Alberti KG, Eckel RH, Grundy SM, Zimmet PZ, Cleeman JI, Donato KA, Fruchart JC, James WP. Harmonizing the metabolic syndrome: a joint interim statement of the International Diabetes Federation Task Force on Epidemiology and Prevention; National Heart, Lung, and Blood Institute; American Heart Association; World Heart Federation; International Atherosclerosis Society; and International Association for the Study of Obesity. Circulation · 2009
- 3.Kalyani RR, Neumiller JJ, Maruthur NM, Wexler DJ. Diagnosis and Treatment of Type 2 Diabetes in Adults: A Review. JAMA · 2025
- 4.Kaur G, Lakshmi PVM, Rastogi A, Bhansali A, Jain S, Teerawattananon Y, Bano H, Prinja S. Diagnostic accuracy of tests for type 2 diabetes and prediabetes: A systematic review and meta-analysis. PLoS One · 2020
- 5.Duan D, Kengne AP, Echouffo-Tcheugui JB. Screening for Diabetes and Prediabetes.
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