A large proportion of prediabetes and diabetes goes undiagnosed when only fasting plasma glucose and/or HbA1c are measured in overweight or obese patients.
OBJECTIVE
The purposes of the study were to determine the prevalence of unrecognized dysglycaemia in overweight (body mass index [BMI] 25-29.9 kg/m(2)) and obese (BMI ≥30 kg/m(2)) patients, to assess the extent to which measures of fasting plasma glucose (FPG) and/or HbA(1c), compared with oral glucose tolerance tests (OGTTs), misdiagnose dysglycaemia, and to determine the factors associated with an isolated abnormal post-OGTT glucose value.


METHODS
OGTT was performed and HbA(1c) was measured in 1283 inpatients with BMI scores ≥ 25 kg/m(2) and no history of dysglycaemia.


RESULTS
Prediabetes was found in 257 (20.0%) subjects (197 with impaired glucose tolerance, 29 with impaired fasting glucose, 31 with both) and diabetes in 77 (6.0%), including 22 with FPG ≥ 7 mmol/L (WHO definition). The sensitivity of FPG >6 mmol/L, FPG >5.5 mmol/L, HbA(1c) ≥ 6% and the recommendations of the French National Agency of Accreditation and Evaluation in Health Care (ANAES) to identify patients with abnormal OGTTs was 29.9, 41.3, 36.8 and 15.6%, respectively. The factors that were independently associated with diabetes in obese women with FPG <7 mmol/L were age (per 10 years: OR 1.54 [1.00-2.11]; P=0.049) and FPG (OR 6.1 [1.4-30.0]; P=0.014), whereas age (OR 1.26 [1.09-1.44]; P<0.01) and waist circumference (per 10 cm: OR 1.17 [1.01-1.33]; P<0.05) were independently associated with dysglycaemia in obese women with FPG <6.1 mmol/L.


CONCLUSIONS
In overweight and obese patients: dysglycaemia is commonly seen; FPG alone, compared with OGTT, failed to diagnose 70% of dysglycaemia cases; FPG >5.5 mmol/L and HbA(1c) ≥ 6.0% are not necessarily substitutes for OGTT; and older age and larger waist circumference should be used to select those obese women with normal FPG who might further benefit from OGTTs to diagnose dysglycaemia.
Cosson
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Department of Endocrinology, Diabetology, Nutrition, Jean-Verdier Hospital, AP-HP, avenue du 14 Juillet, 93143 Bondy cedex, France.
Hamo-Tchatchouang
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Banu
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Nguyen
M-T
MT
Chiheb
S
S
Ba
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H
Valensi
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P
D000328:Adult; D000367:Age Factors; D000368:Aged; D015415:Biomarkers / Q000097:blood; D001786:Blood Glucose / Q000378:metabolism*; D015992:Body Mass Index; D015897:Comorbidity; D003920:Diabetes Mellitus / Q000097:blood / Q000175:diagnosis* / Q000453:epidemiology / Q000209:etiology; D005215:Fasting; D005260:Female; D005602:France / Q000453:epidemiology; D005951:Glucose Tolerance Test; D006442:Glycated Hemoglobin / Q000378:metabolism*; D006801:Humans; D006943:Hyperglycemia / Q000097:blood / Q000175:diagnosis; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000150:complications*; D050177:Overweight / Q000150:complications*; D011236:Prediabetic State / Q000097:blood / Q000175:diagnosis* / Q000453:epidemiology / Q000209:etiology; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D012959:Socioeconomic Factors; D055105:Waist Circumference
D015415:Biomarkers; D001786:Blood Glucose; D006442:Glycated Hemoglobin