A large proportion of prediabetes and diabetes goes undiagnosed when only fasting plasma glucose and/or HbA1c are measured in overweight or obese patients

Diabetes Metab. 2010 Sep;36(4):312-8. doi: 10.1016/j.diabet.2010.02.004.

Abstract

Aims: 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.

Conclusion: 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.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Age Factors
  • Aged
  • Biomarkers / blood
  • Blood Glucose / metabolism*
  • Body Mass Index
  • Comorbidity
  • Diabetes Mellitus / blood
  • Diabetes Mellitus / diagnosis*
  • Diabetes Mellitus / epidemiology
  • Diabetes Mellitus / etiology
  • Fasting
  • Female
  • France / epidemiology
  • Glucose Tolerance Test*
  • Glycated Hemoglobin A / metabolism*
  • Humans
  • Hyperglycemia / blood
  • Hyperglycemia / diagnosis
  • Male
  • Middle Aged
  • Obesity / complications*
  • Overweight / complications*
  • Prediabetic State / blood
  • Prediabetic State / diagnosis*
  • Prediabetic State / epidemiology
  • Prediabetic State / etiology
  • Predictive Value of Tests
  • Retrospective Studies
  • Socioeconomic Factors
  • Waist Circumference

Substances

  • Biomarkers
  • Blood Glucose
  • Glycated Hemoglobin A