Our results show that poor diabetes control, especially in the last trimester, is associated with neonatal hypoglycemia. Furthermore, increased UC C-peptide levels could be used as an early indicator for risk of developing neonatal hypoglycemia and a predictor for babies need neonatal admission.
Major risk factors for developing GDM during pregnancy include increased maternal age, a family history of diabetes, a history of GDM in a previous pregnancy, a history of macrosomia in a previous pregnancy, and an increased pre-gravid body mass index [2]. In our study, 35 (42.17%) mothers had GDM, the mean ± SD of maternal age was 36.03 ± 6.93 years, and the mean ± SD of maternal weight was 77.76 ± 8.60 kg.
In this study, at least one attack of hypoglycemia within the first 3 hours of life developed in IDM in about 65.06% neonates. This is comparable to the findings of a study by Begum et al. [9], in which the occurrence of hypoglycemia was 73.3% within the first 6 hours of life, while in Agrawal et al. [10], only 47% of the infants developed hypoglycemia during the first 2 hours of life. In our study, of a total of 54 patients developing hypoglycemia, most cases were asymptomatic hypoglycemia (96.30%), which is in agreement with the findings of previous studies. For example, in a study by Begum et al. [9], about 93.3% of the hypoglycemic babies were asymptomatic, while in Agrawal et al. [10] and Van Howe et al. [11], 100% of the hypoglycemic babies were asymptotic.
Hypoglycemia is the most common metabolic disorder reported in full-term and preterm infants. The definition of hypoglycemia as well as its clinical significance and optimal time at management remain controversial [12]. Previously, asymptomatic hypoglycemia has been considered to be of no clinical significance [13]. However, numerous studies have demonstrated that even asymptomatic hypoglycemia can have a poor neurodevelopmental outcome immediately after birth [14] and even later on up to school age [15]. Therefore, early detection and management of even asymptomatic hypoglycemia are critically important.
In our study, the demographic characteristics of the mothers were similar in hypoglycemic and normoglycemic groups, such as maternal age, maternal weight, and type and duration of diabetes, with similar results when compared to Begum et al. [9]. In contrast, Agarwal et al. [10] who found that IDMs with hypoglycemia had significantly longer durations of maternal diabetes. In our study, infants with hypoglycemia had higher birth weights than normoglycemic babies, although this difference was not statistically significant. This is in agreement with Dawid et al. [16], who found neither a correlation between birth weight and maternal fructosamine level nor between birth weight and maternal HBA1C level. In contrast, Metzger et al. [17] and Cooper et al. [18] found that infants with a higher birth weight were more likely to develop hypoglycemia and hyperinsulinemia than the control group with a normal birth weight, suggesting physiologic relationships between maternal hyperglycemia and fetal insulin production.
We observed a statistically significant difference between infants developing hypoglycemia and having mothers with poor diabetes control in the last trimester and normoglycemic babies. This finding is in agreement with Griffiths et al. [19] and Fallucca et al. [20], who observed a correlation between infant hypoglycemia and poor maternal diabetes control. In contrast, other researchers found that even in well-controlled diabetic mothers, the incidence of early hypoglycemia in infants is still high, particularly in those mothers who had a longer duration of diabetes [10, 16, 21]. Even for some IDM complications, Vela-Huerta et al. [22] found no correlation between the increased prevalence of asymmetric septal hypertrophy and maternal HbA1C.
Furthermore, in this study, we found a statistically significant increase in UC C-peptide levels in infants who developed hypoglycemia when compared to the control group (P value = 0.005), suggesting that C-peptide can be used as an early predicator for hypoglycemia in IDMs. This finding is comparable with other studies reporting that cord C-peptide levels were inversely related to BG concentrations in the early postnatal period [9, 17, 18, 20]. Furthermore, the increased UC C-peptide level may be associated with infant macrosomia [17, 23] and neonatal septal hypertrophic cardiomyopathy [18]. Therefore hyperinsulemia is the cornstone in the development of many complication in IDM [24].
In conclusion, poor diabetes control, especially in the last trimester, is associated with neonatal hypoglycemia. Furthermore, increased UC C-peptide levels could be used as an early indicator for risk of developing neonatal hypoglycemia and a predictor for babies need neonatal admission. However, further studies with larger sample sizes are needed to determine the cost effectiveness of this relatively costly test before it can be used routinely in daily care practice.