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Antepartum 1-hour glucose value predicts future insulin use
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In pregnant women, 1-hour plasma glucose value after an oral glucose tolerance test predicts future insulin therapy initiation and a postpartum diagnosis of impaired glucose tolerance, according to an analysis of two retrospective studies conducted in Japan.
“In order to ensure normal fetal development and better perinatal outcomes, it is important to establish whether insulin therapy is needed for glycemic control in the early stages of [gestational diabetes],” Takeshi Nishikawa, MD, PhD, of the department of diabetes and endocrinology at Kumamoto Medical Center, Japan, and colleagues wrote in the study background. “Some studies have revealed some factors that underlie the need for insulin therapy for glycemic control, but consistent predictive factors have not been found.”
Nishikawa and colleagues analyzed data from two retrospective studies of patients with gestational diabetes in Japan. For the first study, researchers compared the characteristics of 529 women with gestational diabetes who needed insulin therapy (n = 57) vs. those requiring diet therapy only (n = 472), to identify factors predicting the need for insulin therapy. For the second study, researchers compared characteristics of 185 women who had gestational diabetes from the first study and were found to have IGT after undergoing a 75-g OGTT during the 6- to 12-week postpartum visit. Within the second cohort, 41 women received insulin therapy and 144 women were treated with diet alone. Researchers performed receiver operating characteristic (ROC) curve analysis to identify clinical factors that predicted the need for insulin therapy or the appearance of IGT.
In logistic regression analyses, researchers found that plasma glucose levels after a 1-hour, 75-g OGTT were a predictor of future insulin therapy initiation in pregnant women (OR = 1.023; 95% CI, 1.009-1.037), as were HbA1c (OR = 3.192; 95% CI, 1.177-8.659) and gestational week at gestational diabetes diagnosis (OR = 0.958; 95% CI, 0.921-0.997). In ROC curve analyses, the cutoff value for plasma glucose level after a 1-hour OGTT was 181.5 mg/dL (area under the curve, 0.739; sensitivity, 60%; specificity, 75.8%). The cutoff value for HbA1c was 5.35% (AUC, 0.65; sensitivity, 54.4%; specificity, 65.5%) and the cutoff value for gestational week at gestational diabetes diagnosis was 25.07 weeks (AUC, 0.613; sensitivity, 61.8%; specificity, 58.9%).
Among the women in the second group who underwent the postpartum OGTT, 160 had normal glucose tolerance and 25 (13.5%) had IGT, including three women diagnosed with type 2 diabetes. In logistic regression analyses, researchers found that only plasma glucose value after OGTT at 1 hour and level of ketone bodies in urine were predictors of IGT in postpartum women, with ORs of 1.027 (95% CI, 1.004-1.05) and 1.558 (95% CI, 1.091-2.255), respectively. In ROC curve analyses for the second group, the cutoff value for plasma glucose level after a 1-hour OGTT was 184.5 mg/dL (AUC, 0.77; sensitivity, 68%; specificity, 82.3%) and 0.75 for ketone bodies in a urine test (AUC, 0.7; sensitivity, 68%; specificity, 63.1%).
“To our knowledge, antepartum ketone bodies in a urine test have not been reported as a predictor for postpartum IGT,” the researchers wrote. “The exact reason for this phenomenon is unclear, but there may be a few possible explanations.”
The researchers noted that the presence of high levels of ketones indicates insufficient intake of food and carbohydrates or impaired insulin secretion and insulin action, and that hyperemesis gravidarum may also affect postpartum glucose tolerance and may induce ketonuria.
“If a 1-hour value of more than 180 mg/dL in a 75-g OGTT is observed in pregnant women, we should diagnose women with [gestational diabetes] and give a careful consideration to both their need for insulin therapy in pregnancy and postpartum IGT,” the researchers wrote. – by Regina Schaffer
Disclosures: The authors report no relevant financial disclosures.
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