[Fasting or post-challenge blood glucose values for detection of glucose intolerance in screening for metabolic syndrome?].

INTRODUCTION

The normal-pathological threshold of fasting blood glucose values was modified by the new WHO diagnostic criteria (1999) and, in addition, impaired fasting glucose (IFG) was introduced as a new clinical entity. Nevertheless, the 2-h post-glucose challenge criteria and the concept of the impaired glucose tolerance (IGT) remained unchanged. There is no unequivocal agreement whether new fasting or unchanged post-challenge blood glucose criteria should be used for classification of glucose intolerance.

AIMS

To assess the clinical-laboratory characteristics of metabolic syndrome a screening procedure was performed in hypertensive or obese subjects registered within primary health care and the reliability of the new fasting blood glucose criteria was analysed.

PATIENTS AND METHODS

For inclusion, subjects of both sexes aged from 20 to 65 years exhibited at least one of the following clinical characteristics: hypertension (ongoing antihypertensive treatment or raised (> or = 140/90 mmHg) actual blood pressure), abnormal (> 30.0 kg/m2) body mass index [BMI] or elevated waist-hip ratio (> 0.85 in women, > 0.90 in men). Subjects with known diabetes were not involved. An oral glucose tolerance test (OGTT) with 75 g glucose was performed in each subject. Subjects with complete clinical and laboratory findings were statistically analysed (n = 944; women/men: 545/399; age: 46.1 +/- 7.3 years; BMI 32.2 +/- 5.4 kg/m2; waist-hip ratio 0.90 +/- 0.09; x +/- SD).

RESULTS

In the total cohort newly diagnosed diabetes mellitus (based on the 120 min post-challenge glucose values) was found in 87 subjects (9.2%), IGT was detected in 136 cases (14.4%) while normal glucose tolerance was documented in 721 subjects (76.4%). Using fasting blood glucose values for classification, diabetes mellitus was detected in 79 subjects (8.4%), IFG was found in 124 cases (13.1%) while 741 subjects (78.5%) had normal glucose tolerance. Impaired glucoregulation (IGT + IFG) was found in 223 subjects (IGT alone 99 cases [44.4%], IFG alone 87 cases [39.0%], IGT and IFG in combination 37 cases [16.6%]). The sensitivity and specificity of fasting blood glucose criteria for detecting diabetes were 63.2% and 97.1%, respectively, while those for detecting glucose intolerance (IFG and diabetes as well as IGT and diabetes) were 52.9% and 88.2%, respectively. Clinical characteristics of subjects with abnormal post-challenge but normal fasting blood glucose values (n = 105) did not differ significantly from those of subjects with normal post-challenge but abnormal fasting blood glucose values (n = 85) (age: 46.7 +/- 6.9 years vs 46.7 +/- 6.1 years; BMI: 33.1 +/- 5.4 kg/m2 vs 32.3 +/- 4.5 kg/m2; waist-hip ratio: 0.91 +/- 0.09 vs 0.92 +/- 0.07; p > 0.05).

CONCLUSION

OGTT and 2-h post-glucose challenge criteria should be used for the diagnosis of different categories of glucose intolerance in screening for metabolic syndrome.