Endocrine Abstracts

Recently the American Diabetes Association (ADA) adopted a lower cut off for (IFG) Impaired fasting glucose (greater than or equal to 5.6 millimol per litre). We suggested that performing oral glucose tolerance tests (OGTT), in all subjects with IFG according to the new ADA criteria, would result in very little new diagnosis of Diabetes Mellitus (DM) and to test this hypothesis we reviewed our recent experience with OGTTs.

Between August 2001 and June 2004, 245 standard 75gram OGTT was performed in the diabetes unit of JCMH. The average age of the subjects was 56.7years (range 17-88 years), 129 (52.6%)were male and 116 (47.4%) were female.

The mean fasting plasma glucose (FPG) of the whole group was 6.4 millimols per litre and the mean 2 hours postprandial (pp) was 9 millimols per litre. 113 (46.2%) of the OGTTs were normal. Of the remaining, 73 (29.8%) had DM and 59 (24%) had IFG/IGT (impaired glucose tolerance).

There were 16 subjects who were classified as having IFG by the new criteria who would have been normal by the old criteria. The mean FPG and 2 hours pp glucose in this group was 5.7 and 5.9 millimols per litre respectively. None of this group had either IGT or DM.

This compares with FPG and 2 hours pp glucose levels of 6.5 and 9.7 millimols per litre respectively in patients with FPG greater than or equal to 6.1, a group of 46 of who 22 had IGT and 12 had DM.

We conclude that although IFG denotes a group at high risk of cardiovascular complications, performing OGTT's on all patients with a FPG greater than or equal to 5.6 millimols per litre will result in fewer new cases of DM.