Impaired fasting glycaemia (IFG)

• This has been introduced to classify individuals who have fasting glucose values above the normal range but below those diagnostic of diabetes. (fasting plasma glucose >= 6.1 mmol/l but < 7.0 mmol/l)
• all those with impaired fasting glycaemia (IFG) should have an oral glucose tolerance test to exclude the diagnosis of diabetes, and are actively managed with life style advice
  • the oral glucose tolerance test reveals a 2 hour result of <7.8 mmol/l
• the relative risk of progressing to diabetes for patients with IFG is 1.1-2.2% per year
• patients with IFG may also have manifestations of metabolic syndrome. There is also an increased cardiovascular risk associated with patients with IFG compared with people with fasting glycaemia in the normal range. Patients with IFG need to have their macrovascular risks assessed and the calculated risk increased because of their IFG - a doubling of risk to allow for increased risk has been suggested
• these people should be followed up annually to reassess glucose regulation and all other cardiovascular risk factors

Note - IFG and IGT differ in the site of insulin resistance as well as the pattern of insulin secretion. IFG is characterized predominantly by hepatic insulin resistance and normal muscle insulin sensitivity. People with IFG show a defect in early phase insulin secretory response to glucose. IGT is mainly associated with muscle insulin resistance.(2)

Reference:

1. Ferrannini E, Gastaldelli A, Iozzo P. Pathophysiology of prediabetes. Med Clin North Am. 2011 Mar;95(2):327-39, vii-viii.
2. Nathan DM et al. American Diabetes Association. Impaired fasting glucose and impaired glucose tolerance: implications for care. Diabetes Care. 2007 Mar;30(3):753-9