Aims/hypothesis: To study the risk of women with impaired fasting glucose (IFG) as against impaired glucose tolerance (IGT) developing diabetes.
Methods: Oral glucose tolerance tests (75 g) were done in 265 women selected at random at baseline (age 55-57 years) and at a 10-year follow-up. Of the women 42 had IFG/NGT (fasting glucose 6.1-6.9 mmol/l, 2-h glucose < 7.8 mmol/l), 66 IGT/ NFG (2-h glucose 7.8-11.0 mmol/l, fasting glucose < 6.1 mmol/1), 30 IGT/IFG and 127 NFG/NGT.
Results: The 10-year progression to diabetes was similar in IGT/NFG (12.1%) and IFG/NGT groups (11.9%, p = 0.97). In IGT/IFG, 20.0% had developed diabetes, which was not significantly higher than in IFG/NGT and IGT/NFG (p = 0.53). In NFG/ NGT at baseline, only 3.9 % had developed diabetes, which was lower than in the other groups (p = 0.023).
Conclusion/interpretation: Fasting and 2-h glucose concentrations are equally good in predicting diabetes development over a 10-year period in Caucasian postmenopausal women. Because IGT is more common than IFG, measuring only fasting glucose concentrations would, however, result in missing a prediabetic stage in a large group of people at risk for diabetes and cardiovascular diseases.