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Mild glucose abnormalities in pregnancy linked to postpartum diabetes risk
 
 
  By Anthony J. Brown, MD
 
NEW YORK (Reuters Health) - Any degree of abnormal glucose homeostasis during pregnancy is predictive of glucose intolerance 3 months after delivery, according to a report in the October issue of Diabetes Care.
 
The results, according to the authors, suggest that antepartum screening for gestational diabetes is useful in gauging a woman's future risk of pre-diabetes and type 2 diabetes.
 
"It is well recognized that women with gestational diabetes are at increased risk of developing type 2 diabetes in the future," lead author Dr. Ravi Retnakaran, from Mount Sinai Hospital in Toronto, told Reuters Health. "The novel finding of our study is that even women with mildly abnormal glucose levels in pregnancy have an increased risk of developing pre-diabetes or diabetes after their pregnancy."
 
Dr. Retnakaran added, "We weren't surprised by this finding, as we had hypothesized that any degree of glucose intolerance in pregnancy should predict an increased future risk of pre-diabetes or diabetes, although we were surprised by the magnitude of this increased risk."
 
The study involved 487 women who underwent antepartum diabetes screening with a glucose challenge test (GCT) and a diagnostic oral glucose tolerance test (OGTT). In addition, the OGTT was repeated at 3 months postpartum to assess glucose homeostasis.
 
On the basis of the two antepartum tests, the women were divided into four groups: 1) gestational diabetes mellitus, 2) gestational impaired glucose tolerance, 3) abnormal GCT with normal OGTT, and 4) normal GCT and normal OGTT.
 
The prevalence of postpartum glucose intolerance (diabetes or pre-diabetes) rose as the severity of abnormal glucose homeostasis during pregnancy increased, Dr. Retnakaran and colleagues found. The prevalence ranged from just 3.2% for patients with normal GCT and normal OGTT to 32.8% for those with gestational diabetes (p < 0.0001).
 
Compared with normal glucose findings during pregnancy, abnormal GCT/normal OGTT, gestational impaired glucose tolerance, and gestational diabetes increased the risk of postpartum glucose intolerance by 3.6-, 5.7-, and 14.3-fold, respectively.
 
The results also show that insulin sensitivity and pancreatic beta-cell function, both during pregnancy and at 3 months postpartum, fell as glucose homeostasis during pregnancy went from normal to gestational diabetes (p < 0.0001).
 
"The significance of our study rests in its illustration of the concept that the spectrum of abnormal glucose homeostasis in pregnancy identifies a continuum of risk for postpartum glucose intolerance and that this spectrum extends to levels of antepartum dysglycemia far less severe than gestational diabetes mellitus," the research team concludes.
 
"Our results suggest that the use of supplementary continuous glucose monitoring as an educational tool during pregnancy is associated with improved maternal glycaemic control. The results were clinically and statistically significant, as the infants of mothers in the intervention arm (continuous glucose monitoring) had a lower birth weight and a reduced risk of macrosomia than those of mothers in the control arm (standard antenatal care).
 
The observed differences in maternal HbA1c levels, reflecting mean blood glucose levels over the preceding 4-6 weeks, began to emerge at 28 weeks but did not reach statistical significance until after 32 weeks' gestation. Earlier studies of postprandial finger prick testing also found better glycaemic control in late gestation, with improvements in blood glucose levels during the second and third trimesters and in HbA1c levels before delivery."
 
What is already known on this topic
 
Continuous glucose monitoring is a potentially beneficial educational tool, with benefits on glycaemic control NICE have called for research during pregnancy, to focus on pregnancy complications and infant outcomes
 
What this study adds
 
Continuous glucose monitoring is associated with improved maternal glycaemic control and reduced infant birth weight and risk of macrosomia
 
The beneficial effects on pregnancy complications potentially offer longer term health benefits for the infants of mothers with diabetes
 
 
 
 
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