[The usefulness of basal blood glucose and glycosylated hemoglobin for the detection of abnormal glucose tolerance in the relatives of patients with type-2 diabetes mellitus].

BACKGROUND

Type 2 diabetes mellitus (DM 2) constitutes today one of the most important problems in terms of health. Nowadays, there is special interest to identify those subjects with a high risk for developing the disease. Our study aimed to evaluate fasting glycemia and glycated hemoglobin in the screening of defects in oral glucose tolerance, in relatives of patients with DM 2.

SUBJECTS AND METHODS

111 relatives of patients with DM 2 were consecutively included in the study. Glycated hemoglobin (HbA1c, DCA 2000) was measured, afterwards an oral glucose tolerance test (OGTT) was performed. 120 min glycemia (G120) classified oral glucose tolerance as: normal (NGT), impaired glucose tolerance (IGT) and DM. In a first subgroup (n = 80) the equation to predict G120 was obtained (G120 estimated) from the basal glycemia (GO) and HbA1c. In a second subgroup (n = 31), G120 observed after the OGTT (G120 observed) and G120 estimated were compared. Finally, sensitivity, specificity and positive predictive value (PPV) for different cutpoints of GO and G120 were estimated, in order to identify those subjects with abnormal glucose tolerance (IGT and DM).

RESULTS

Considering the results from the first subgroup of subjects, G120 was independently related with GO (R2 = 0.64) and with HbA1c (R2 = 0.62). When GO and HbA1c were considered altogether R2 value was 0.73. When data from the second subgroup of subjects was analysed we did not find any differences between observed G120 and G120 estimated by the equation. The sensitivity, specificity and PPV to detect abnormalities in oral glucose tolerance of estimated G120 were 80, 76 and 61%, respectively. Optimal values of these parameters were obtained with GO 98-102 mg/dl and Hba1c 5.6-5.8%.

CONCLUSIONS

Our results confirm that the measurement of GO and HbA1c in first degree relatives of patients with DM 2 is extremely useful to identify those subjects in which abnormal oral glucose tolerance is highly probable.