Impaired glucose tolerance (IGT)

This is a stage of impaired glucose regulation (Fasting plasma glucose < 7.0 mmol/l and OGTT 2-hour value >= 7.8 mmol/l but < 11.1 mmol/l).

The risk of subsequent conversion to diabetes is about 4.7% per year in Caucasians and higher in some ethnic minority groups.

• these people should be followed up annually to reassess glucose regulation and all other cardiovascular risk factors (2)

The incidence of impaired glucose tolerance is:

• 17% of those aged 40-65 in the UK (3)
• 11% of those aged 20-74 in the US (4)

Complications of impaired glucose tolerence include:

• cardiovascular disease - in middle aged men with glucose intolerence have double the risk of death from cardiovascular disease (5)
• study evidence has revealed an increased mortality risk associated with IGT (6)
  • impaired glucose tolerance was associated with an increased mortality risk (HR 1.5, 95% CI 1.1 to 2.0)

Reference:

• (1) Pulse 2004; 64 (6).
• (2) JBS2: Joint British Societies' guidelines on prevention of cardiovascular disease in clinical practice. Heart 2005; 91 (Supp 5).
• (3) Brown, DC et al . Height and glucose tolerence in adult subjects.Diabetologia 1991; 34:531-3.
• (4) Harris, M . Impaired glucose tolerence in the US population.Diabetes Care 1989; 12: 464-74.
• (5) Fuller, JH et al. Coronary heart disease risk and impaired glucose tolerence: the Whitehall study. Lancet 1980; 1: 1373-6
• (6) Barr EL et al. Risk of cardiovascular and all-cause mortality in individuals with diabetes mellitus, impaired fasting glucose, and impaired glucose tolerance: the Australian Diabetes, Obesity, and Lifestyle Study (AusDiab).Circulation. 2007 Jul 10;116(2):151-7