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Glycosilated hemoglobin A1C in pregnancies with gestational diabetes

Gestational diabetes in known to be one of the main complications of pregnancy, as it is found in 3% of all pregnancies. Poor metabolic control during pregnancy is associated with increased risk of spontaneous abortions, preeclampsia, macrosomic newborns and stillborns. Good metabolic control during pregnancy will significantly decrease rates of complications mentioned before. To achieve good metabolic control diabetic nutrition is essential, in 10-15% insulin therapy is also required, and, of course, appropriate antenatal surveillance. In surveillance of diabetic pregnancies the team of experts, including obstetrician, diabetologist, neonatologist, anesthesiologist and nurse is necessary. Glycosylated proteins. Binding of glucose to proteins is non-enzymatic and slow reaction, dependable on glucose concentration, pH and time. By binding of glucose to beta-chain of hemoglobin, the unstable structure called aldimine is formed. Stable ketoamine is created by slow Armador's transformation. Diagnostically the most important and quantitatively largest fraction is hemoglobin A1c (HbA1c). Strong correlations have been found between concentration of HbA1c and: glicosuria, fasting glucose level and mean blood glucose profile during last 2 to 3 months. HbA1c gives the best information about metabolic control during last 8 weeks. AIMS OF THE STUDY were: § To investigate levels of HbA1c in pregnancies with gestational diabetes and healthy pregnancies. § To investigate how do levels of HbA1c help in detection and control of pregnancies with carbohydrate metabolism impairment. § To compare levels of HbA1c with spontaneous abortion and preterm delivery rate. § To compare body weight increase of pregnant women with levels of HbA1c in both study groups. § To compare alteration from ideal body weight with levels of HbA1c in both study groups. § To compare newborn weight with levels of HbA1c. MATERIALS AND METHODS. The study comprised 140 pregnant women. Women were subsequently divided in two groups, one with 46 healthy pregnant women and the other with 94 pregnant women with gestational diabetes. Oral glucose tolerance test (oGTT), with standard 75-gr glucose loads, was performed according to WHO protocol between 20th and 28th week of gestation, in all pregnancies, in order to diagnose gestational diabetes. In all women, HbA1c with modified chromatographic technique with use of prepared reagencies and microcolones from "Dialab", oGTT and fasting glucose level were analyzed. Obtained levels of HbA1c were analyzed compared with time of delivery, regarding each study group. In all pregnancies following parameters were analyzed: newborn weight, Apgar score in 1' and 5', perinatal mortality and neonatal complications. Body weight of women at term, weight increase and alteration from ideal body weight were also analyzed and correlated with detected levels of HbA1c. Data were analyzed using personal computer and SPSS 10.0 statistical program, with &#967; 2 test, Student t-test, ANOVA, table of contingence and linear regression. RESULTS. Mean maternal age in healthy pregnant women was 29, 76 +/- 5, 79 years vs. 32, 33 +/- 6, 37 years in women with gestational diabetes, which was statistically significant difference (F=9, 34 p=0, 003). Mean body weight of healthy pregnant women was 81, 96 +/- 14, 73 kg vs. 85, 00 +/- 12, 62 kg in women with gestational diabetes. When body weight gain was compared between two groups, significantly higher gain was observed in the group with gestational diabetes in comparison to healthy group. Women with gestational diabetes obtained higher alteration from ideal body weight (178.3 +/- 160.4%), which was significantly different from the group of healthy women (62, 0+/- 131, 1%). Pediatric evaluation of gestational age showed that the average diabetic pregnancy was terminated before normal pregnancy. No congenital anomalies in any of the groups were found. In healthy pregnancies group there were three preterm deliveries (6, 38%) vs. 20 preterm deliveries (21, 0%) in diabetic pregnancies group. In healthy pregnancies group there was no spontaneous abortion, while there was one in diabetic pregnancies group. In healthy pregnancies group there was no level of HbA1c > 8%, and in diabetic pregnancies group level of HbA1c >8% was found in 9 cases (9, 5%). Statistically significant correlation factor was found between levels of HbA1c and body weight gain (r=0, 54 ; p<0, 001) ; pregnant women with higher weight gain obtained higher levels of HbA1c. Statistically significant correlation factor was found between levels of HbA1c and alteration from ideal body weight (r=0, 48 ; p<0, 0001). Obese pregnant women obtained higher level of HbA1c. Also, statistically significant correlation factor was found between newborn weight and levels of HbA1c in maternal blood (r=0, 51 ; p<0, 001). DISCUSSION. Our study confirmed that level of HbA1c was significantly higher in patients who had spontaneous abortion (8, 98 +/- 2, 79%) ; compared with those who had preterm (7, 10 +/- 1, 78%) or on term (6, 33 +/- 1, 98%) delivery. Rate of macrosomic newborn was 20, 0% in diabetic pregnancies group, compared with 3, 5% in general population. Analyses showed that gestational age at delivery and level of HbA1c in early pregnancy, independently, both have influence on appearance of neonatal complications. Statistically significant correlation factor was found between maternal body weight gain and level of HbA1c (r=0, 54 ; p<0, 001). Also, statistically significant correlation factor was found between levels of HbA1c and alteration from ideal body weight (r=0, 48 ; p<0, 0001). These results proved already established theory that maternal hyperglycemia leads to fetal hyperglycemia, which results in fetal hyperinsulinemia, improved utilization of glucose within cells, lipid storage into cells, and, at the end, macrosomic newborns. High levels of HbA1c are proof of poor metabolic control. Early diagnosis and treatment of pregnancies with impaired glucose tolerance and gestational diabetes reduce rate of macrosomic newborns and , by that, reduce newborn mortality and morbidity, too. CONCLUSIONS. § By good glycemic regulation and continuous surveillance of pregnancies with gestational diabetes, it is possible to decrease rates of stillborns, neonatal complications and macrosomic newborns. § Early diagnosis and treatment of gestational diabetes (incidence in our population is 2.5%) will decrease perinatal mortality and rate of macrosomic newborns, and will also prevent development of clinical diabetes in these women later in life. § Correlation between levels of HbA1c and body weight gain during pregnancy was found. § Correlation between newborn weight and levels of HbA1c in maternal blood was found.

glycozilated hemoglobin; gestational diabetes

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