Follow up testing of hyperglycaemia during hospital admission: combined use of fasting plasma glucose and HbA1c.

A high proportion of those with hyperglycaemia in hospital have diabetes or impaired glucose tolerance at one year. Initial testing with fasting plasma glucose and HbA1c avoided oral glucose tolerance test in 76% of cases. Use of HbA1c detected otherwise missed diabetes and impaired glucose tolerance. A random plasma glucose of > or = 7.8 mmol/L in hospital targets patients who should be tested for impaired glucose tolerance or diabetes following discharge.