Prediabetic states

Pre-diabetic states are metabolic conditions  that share features with diabetes but do not meet the diagnostic criteria

• There are two main conditions to consider:
  • Impaired fasting glucose (IFG)
  • Impaired Glucose Tolerance (IGT)

Definitions

These definitions are based on NICE criteria (up to date as of Nov 2018) which are in turn based on WHO criteria

• Normal is defined as
  1. Fasting glucose ≤6.0 mmol/l
  2. Postprandial/Random glucose ≤7.8 mmol/l

• Diabetes is defined with either:
  1. Fasting glucose ≥7 mmol/l
  2. Postprandial/random glucose >11 mmol/l
  • Anything meeting these is therefore diabetes by definition

• Impaired fasting glucose (IFG) – there is an impaired level of glucose when fasting (but tolerance to glucose intake is normal)
  • This is defined as:
    1. Fasting glucose from 6.1- 6.9 mmol/l
    2. Normal postprandial glucose (<7.8)

• Impaired Glucose Tolerance (IGT) – there is an impaired tolerance to glucose intake (but fasting glucose is normal)
  • This is defined as:
    1. Normal Fasting glucose (I.e. <6 mmol/L )
    2. Abnormal 2 hour glucose = 7.8 – 11.0 mmol/l
       • Would be considered diabetic if >11

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Summary

There are several possible outcomes based on the combination of glucose levels

1. Both ≤6.0 and <7.8 = Normal
2. 6.1-6.9 ±  7.8-11.0 =  IFG ± IGT
   • NB due to the values a patient can have both IGT/IFG without having Diabetes
3. Either ≥7.0 or ≥11.1 = Diabetes

• IFG and IGT are independent risk factors for diabetes development
  • Highlight different aspects of glucose metabolism abnormalities – i.e. fasting and post-prandial dysfunction respectively
  • IGT has a higher risk of progression

• Both require annual review with lifestyle advice
  • In practice both are managed as diabetes