The 1-h 50-g glucose challenge does not predict large-for-gestational-age infants

Evaluating the therapeutic approach in pregnancies complicated by borderline glucose intolerance: a randomized clinical trial

AIMS

Most studies relating minor gestational metabolic alterations to macrosomia refer to glucose intolerance classified on the basis of the National Diabetes Data Group or previous World Health Organization diagnostic thresholds. Our aim was to evaluate the consequences of very mild forms of gestational glucose intolerance, defined by an elevated 50-g glucose challenge test followed by a normal oral glucose tolerance test, using the more restrictive Carpenter and Coustan's criteria (Borderline Gestational Glucose Intolerance, BGGI).

METHODS

Three hundred BGGI women were randomly assigned to: Group A (standard management), Group B (dietary treatment and regular monitoring). A control group (C) was also considered. Newborns were classified as macrosomic, large (LGA), or small for gestational age (SGA).

RESULTS

The three groups were similar in age, body mass index and parity. Therapy in Group B significantly improved fasting (from 4.68 +/- 0.45 to 4.28 +/- 0.45 mmol/l) and 2-h postprandial glycaemia (from 6.01 +/- 0.57 to 5.13 +/- 0.68 mmol/l). Fasting glycaemia at delivery was significantly lower in B (4.20 +/- 0.38 mmol/l) than in A (4.84 +/- 0.45 mmol/l), and was also lower than in C (4.31 +/- 0.39 mmol/l). Significantly fewer LGA babies were born to Group B (6.0%) than Group A (14.0%) and Group C (9.1%). No difference was found in the SGA rate. The neonatal Ponderal Index was higher (P = 0.030) in group A (2.73 +/- 0.35) than in C (2.64 +/- 0.30) and B (2.64 +/- 0.24).

CONCLUSIONS

Even very mild alterations in glucose tolerance can result in excessive or disharmonious fetal growth, which may be prevented by simple, non-invasive therapeutic measures.

Screening for gestational diabetes in a multi-ethnic population

A multi-ethnic population was screened for gestational diabetes mellitus (GDM) using a venous plasma glucose estimation, 1 h following a standard 50 g glucose load. A significant difference in the ethnic distribution of screen-positivity was found. Amongst the screen-positive group the odds ratio (OR) for special care baby facility (SCBU) admission and birthweight > 3999 g were both increased (OR = 1.87 and 1.99). Only limited diagnostic testing by a glucose tolerance test (GTT) could be achieved for the screen-positive population. For patients with confirmed GDM (two or more abnormal values on a GTT) the OR for SCBU admission was further increased to 5.1, while the OR for increased birthweight was only 1.34. Clinical attention should be directed towards outcome assessment in order to properly evaluate the nature of and place for screening for GDM in multi-ethnic populations.

Glucose tolerance test during pregnancy: the significance of one abnormal value

To determine the perinatal impacts of one abnormal oral glucose tolerance test (GTT) value, we conducted a retrospective study of pregnancy outcome in our population. Pregnant women (4314) were screened for gestational diabetes (GDM) between 24 and 32 weeks with the 50-g glucose challenge test and 183 were directly tested with the 100-g GTT. The subjects who had a serum glucose value equal or greater than 7.8 mmol/L 1 h after a 50-g glucose challenge were scheduled for a 100-g GTT (904). Another 32 subjects, who were not screened, were found to have gestational diabetes identified by repeated fasting and postprandial serum glucose measurements. Retrospectively, the study population was divided in four groups: I, normal (4138); II, GDM (237); III, subjects with one abnormal GTT value treated like GDM (85); IV, subjects with one abnormal GTT value untreated (69). Patient characteristics of groups II, III, and IV were similar. The area under the glycemic curve was similar between groups III and IV and was statistically inferior to that of Group II. GTT periodicity was the greatest in group II. Group II showed a higher rate of delivery before 37 weeks, of chronic and pregnancy induced hypertension, and of cesarian section but groups III and IV were not statistically different from group I.(ABSTRACT TRUNCATED AT 250 WORDS)