Prognosis of patients with positive screening but negative diagnostic test for gestational diabetes

This is a retrospective study that is designed to investigate the prognosis of the patients with abnormal diabetes screening test and a negative 100 g oral glucose tolerance test that is accepted as the diagnostic test for gestational diabetes mellitus (GDM).

The records of 281 pregnant patients were reviewed. The data of the patients divided into groups with normal diabetes screening (1 h/50 g oral glucose tolerance test) and abnormal diabetes screening. The patients with abnormal diabetes screening were further divided into all values normal in 100 g Oral glucose tolerance test (OGTT), one value abnormal in 100 g OGTT and GDM subgroups. The prognosis of these patients was reanalyzed concerning the complications that may be attributed to glucose intolerance.

Abnormal diabetes screening test was detected in 89 patients (31.6%) and 14 cases were diagnosed as GDM (4.9%). The data of 9 patients were not suitable to analyze. In 31 cases out of 80 (38.75%), an obstetric complication was detected. The rate of similar complications was 27.0% (52/192) in the control group. The difference in the rate of complications was not statistically significant (p>0.05). When the patients with one value abnormal in 100 g OGTT, were further evaluated, the complication rates were 3/9 (33.3%) for the 1st hour abnormal patients, 1/1 for the 2nd hour abnormal patients and 1/1 for the 3rd hour abnormal patients. When the values of 100 g OGTT were compared in complicated and uncomplicated cases, the difference between the groups was not statistically significant (p>0.05).

100 g OGTT is the universal diagnostic test for GDM. There is a major subgroup of patients whose screening positive but diagnostic test (100 g OGTT) negative. These patients seem to be prone to develop obstetric complications related to glucose intolerance but there is not a proper means to detect these patients in clinical practice.