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

Aim. To follow up patients without known diabetes, but with hyperglycaemia in hospital for diabetes at one year. Methods. 159 patients with a random plasma glucose greater than or equal to 7.8 mmol/L recorded during hospital admission were sent a questionnaire an d invited to have the following test one year following discharge: fasting plasma glucose, HbA1c and fasting lipid profile. Those with a fasting plasm a glucose greater than or equal to 5.5 and <7.0 mmol/L, and/or those with a HbA1c greater than or equal to 6.0%, were asked to have an oral glucose to lerance test. Those with a fasting plasma glucose greater than or equal to 7.0 mmol/L were defined as having diabetes. Results. There were 88 full responses. Nineteen (21.6%) had diabetes and ni ne impaired glucose tolerance. Hb1Ac was greater than or equal to 6% in fiv e subjects with a fasting plasma glucose <5.5 mmol/L. Two had impaired gluc ose tolerance and one diabetes. If a random plasma glucose in-hospital of 1 0 mmol/L is used as a threshold for later testing, as suggested by previous studies, then 25% of those with an abnormal result would have been missed. Conclusions. A high proportion of those with hyperglycaemia in hospital hav e 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 glu cose tolerance. A random plasma glucose of greater than or equal to 7.8 mmo l/L in hospital targets patients who should be tested for impaired glucose tolerance or diabetes following discharge.