Type 2 diabetes (T2DM) is known to be underdiagnosed. Tests for diagnosis include fasting plasma glucose (FPG), oral glucose tolerance test (OGTT) and HbA1c. HbA1c can be tested in non-fasting conditions. Therefore, general practitioners almost no longer execute OGTT’s. We evaluated the performance of OGTT versus HbA1c in a population consisting of overweight and obese subjects, which can be considered a ‘high risk’ population.
Research design and methods:
A total of, 1241 overweight and obese subjects without a history of diabetes (male/female: 375/866, age 44±13 years, body mass index 38.0±6.1 kg m−2) were tested for glucose tolerance status using FPG, OGTT and HbA1c.
Exactly, 46.8% were found to have prediabetes and 11.9% were newly diagnosed with T2DM (male/female=18.9/8.9%) using ADA criteria. Testing only HbA1c would have resulted in 78 subjects being diagnosed with T2DM, but 47.3% of newly diagnosed patients would have been missed if OGTT would not have been done. Exactly 581 subjects were diagnosed with prediabetes, 1.4% subjects had impaired fasting glucose (IFG) 30.5% had impaired glucose tolerance (IGT), 5.1% subjects had a combined IFG+IGT, and 9.8% had an isolated elevated HbA1c (5.7–6.4%). Of the 581 subjects with prediabetes, 257 had an HbA1c <5.7%. Therefore, 44.2% subjects would have been missed when OGTT would not have been done.
In a population with only overweight and obese adult subjects, 46.8% were diagnosed with prediabetes and 11.9% were newly diagnosed with diabetes. Exactly, 5.6 and 20.7% of total population met the diagnostic criteria of the OGTT for diabetes and prediabetes, respectively, but did not meet the diagnostic criteria of the HbA1c. These data suggest that not performing an OGTT results in significant underdiagnose of T2DM in an overweight and obese adult population.
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We thank the nursing staff and all patients for making this observational study possible. The results of this study were presented in part at the 75th Scientific Sessions of the ADA (American Diabetes Association), Boston, USA, June 2015.
All authors made important intellectual contributions to the conception and design of the study. Every author reviewed and provided comments on manuscript drafts and gave final approval of this version to be published. CEMDB and LFVG were responsible for the final design of the protocol. LFVG recruited patients and was responsible for the database. All authors implemented the study protocol and acquired data. ASM, CEMDB, IM and AV performed the statistical analysis. ASM, ED and CEMDB drafted the manuscript.
The authors declare no conflict of interest.
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Meijnikman, A., De Block, C., Dirinck, E. et al. Not performing an OGTT results in significant underdiagnosis of (pre)diabetes in a high risk adult Caucasian population. Int J Obes 41, 1615–1620 (2017). https://doi.org/10.1038/ijo.2017.165
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