The Effects of Hypoglycaemia and Hyperglycaemia on Pregnancy Outcome

Incidence Rate of Type 2 Diabetes Mellitus after Gestational Diabetes Mellitus: A Systematic Review and Meta-Analysis of 170,139 Women

OBJECTIVE

The reported incidence of type 2 diabetes mellitus (T2DM) after gestational diabetes (GDM) varies widely. The purpose of this meta-analysis was to define the incidence rate of T2DM among women with a history of GDM and to examine what might modulate the rate. Research Design and Methods. We searched PubMed and Embase for terms related to T2DM after GDM up to January 2019. Large cohort studies with sample size ≥300 and follow-up duration of at least one year were included. Data from selected studies were extracted, and meta-analysis was performed using the random-effects model. Subgroups analyses were based on the sample size of gestational diabetes, geographic region, maternal age, body-mass index, diagnostic criteria, and duration of follow-up.

RESULTS

Twenty-eight studies involving 170,139 women with GDM and 34,627 incident cases of T2DM were identified. The pooled incidence of T2DM after GDM was 26.20 (95% CI, 23.31 to 29.10) per 1000 person-years. Women from Asia and those with older age and higher body mass index seem to experience higher risk of developing T2DM. The incidence rate of T2DM was lowest when applying IADPSG (7.16 per 1000 person-years) to diagnose GDM. The risk of developing T2DM after GDM increased linearly with the duration of follow-up. The increments per year of follow-up were estimated at 9.6‰. The estimated risks for T2DM were 19.72% at 10 years, 29.36% at 20 years, 39.00% at 30 years, 48.64% at 40 years, and 58.27% at 50 years, respectively.

CONCLUSIONS

The findings of very high incidence of T2DM after GDM add an important insight into the trajectory of the development of T2DM in the long-term postpartum periods, which could provide evidence for consultant and might motivate more women with GDM to screen for T2DM. This trial is registered with PROSPERO identifier CRD42019128980.

Association of Low Maternal Plasma Glucose after Oral Glucose Challenge Test with Small for Gestational Age Neonate

Aims and objectives

To study the association of low maternal plasma sugar with birth weight and neonatal morbidity.

Materials and methods

Glucose challenge test was performed in low risk women, the birth weight and neonatal morbidities were compared between women with low GCT (<88 mg/dl) and normal GCT (88-139 mg/dl).

Results

Incidence of small for gestational age (<2500 gm) was significantly more in women with low GCT (17.3% vs 7.3%), but difference in NICU admission between the two groups was not significant statistically.

Conclusion

Prevalence of small for gestational age neonate was significantly higher in women with low GCT compared to women with normal GCT.

How to cite this article

Bhat RG, Bhagya KV, Kumar P. Association of Low Maternal Plasma Glucose after Oral Glucose Challenge Test with Small for Gestational Age Neonate. Int J Infertility Fetal Med 2012;3(1):22-25.

A spectrum of glucose thresholds may effectively prevent complications in the pregnant diabetic patient

This article outlines the probable positive relationship between levels of maternal glycemia and perinatal morbidity and mortality. A spectrum of different glucose thresholds can be established and used appropriately to prevent each complication. This article also outlines the concept of normality and what definitions of normality should be used to evaluate the relationship between the level of glycemia and perinatal outcome. Definitive conclusions are hampered by a lack of uniformity in definitions and interventions, and by a failure in some analyses to control for confounding variables. However, it is suggested that different levels of glycemia are required to prevent different diabetic complications. Thus, although it is not always possible to achieve targeted levels of glycemic control in all patients, any improvement will be beneficial because it will affect fetal complications associated with that glucose threshold.

Level of glycemia and perinatal outcome in pregestational diabetes

This article provides the reader with relevant information regarding the association between level of glycemia and perinatal outcome in preexisting diabetes. Although the glycemic profile is a continuum in nature, different thresholds of glucose are associated with fetal complications such as stillbirth, spontaneous abortion, congenital anomalies, fetal macrosomia, and metabolic and respiratory complications. For each complication, a different targeted threshold of normality is required. Thus, although it is not always possible to achieve optimal glycemic control in all patients, any improvement will be beneficial because it will reduce the rate of complications for a given glucose threshold.

Identification and treatment of women with hyperglycaemia diagnosed during pregnancy can significantly reduce perinatal mortality rates

We wished to determine whether gestational diabetes was associated with an increased perinatal mortality rate, and to investigate the cause for the observed increase in the incidence of gestational diabetes. We therefore reviewed the results of glucose tolerance tests and pregnancy outcome in 116,303 pregnancies, 1971-1994, at the Mercy Hospital for Women. The main outcome measurements were the presence or absence of gestational diabetes, and perinatal mortality. Over the entire period of the study, gestational diabetes was associated with an increased risk of perinatal mortality (Mantel-Haenszel adjusted odds ratio 1.53, 95% CI 1.13-2.06, p = 0.0069). Women with gestational diabetes that was only diagnosed retrospectively had a higher perinatal mortality rate than their contemporaries with normal glucose tolerance (OR 2.31, 95% CI 1.37-3.91, p = 0.0025). Women in whom a glucose tolerance test was not performed continued to have a higher perinatal mortality rate than women who were tested (adjusted OR 2.21, 95% CI 1.56-3.12, p < 0.00001). There has been an increase in the prevalence of gestational diabetes from 2.9% to 8.8%. Some of this is due to changes in population characteristics (increases in maternal age, obesity and proportion from South-East Asia), but there was still an independent increase over time. We conclude that identification and treatment of women with gestational diabetes can reduce perinatal mortality rates. Similarly to diabetes mellitus in the total population, the prevalence of gestational diabetes has increased over time.

Excessive birth weight and maternal glucose tolerance--a 19-year review

The incidence of birth-weight of 4,540 g (10 lb) or more rose from 0.87% in the years 1971 to 1977 to 1.16% in the 12 years from 1978 to 1989 with a concomitant increase in hyperglycaemia in our antenatal population. The relationship between excessive birth-weight and maternal glucose tolerance was investigated in the light of these observations. The results from glucose tolerance tests performed routinely during the pregnancies of 510 women who delivered infants with a birth-weight of 4,540 g or more were compared with those from a control series of 5,003 women with consecutively tested pregnancies. Glucose tolerance in subsequent pregnancies was also compared with the control series, and in 1991 the study group women were investigated for emergence of permanent diabetes mellitus. Excessive birth-weight was associated with maternal hyperglycaemia (p < 0.05) but not with gestational diabetes; 79% of infants with birth-weight > or = 4,540 g were born to mothers who were not hyperglycaemic. There was no increase in glucose intolerance in subsequent pregnancies in the study group and only 2 of 49 women with follow-up testing had diabetes mellitus. Birth-weight > or = 4,540 g occurred in 1.1% of the total population and 1.1% of women with gestational diabetes, and was related to maternal hyperglycaemia in about 1 in 5 cases. The increased incidence of excessive birth-weight infants was not related to the increased incidence of gestational diabetes in our pregnant population. Birth-weight > or = 4,540 g had a poor association with later development of diabetes.

Long-term implications of gestational diabetes for the mother

Women with GDM have a greater risk of developing diabetes in the future compared with those women who have normal glucose tolerance during pregnancy. Using life table techniques, 17 years after the initial diagnosis of GDM, 40% of women were diabetic compared with 10% in a matched control group of women who had normal glucose tolerance in pregnancy. The incidence of diabetes was higher among women who were older, more obese, of greater parity and with more severe degrees of glucose intolerance during pregnancy. Diabetes also occurred more commonly among women who had a first-degree relative who was diabetic, in women born in Mediterranean and East Asian countries, and in those who had GDM in two or more pregnancies. Despite differing testing techniques and varying criteria for the diagnosis of GDM, follow-up studies from across the world consistently show a higher rate of subsequent diabetes among GDM mothers. NIDDM is associated with increased morbidity and a higher mortality rate, especially in women. Cardiovascular and cerebrovascular diseases are the leading causes of death. High lipid levels, hypertension and obesity are often already present when diabetes is diagnosed and may antedate the development of overt diabetes; treatment of diabetes at this stage may therefore be too late to prevent complications occurring. A follow-up programme for women with GDM facilitates screening of a group known to be at increased risk of developing diabetes so that the diagnosis can be made before associated risk factors for complications develop. Intervention in the form of counselling regarding cigarette smoking, exercise and a healthy, high-residue, unrefined carbohydrate, low cholesterol diet, given together with weight monitoring, may prevent the onset of both diabetes and its associated cerebrovascular and cardiovascular problems.

Polyhydramnios and associated maternal and fetal complications in singleton pregnancies

During the 10-year period 1 January 1979 to 31 December 1988, polyhydramnios occurred in 537 patients with singleton pregnancies delivered at the Mercy Maternity Hospital. Associated maternal and fetal complications and the perinatal outcome of these pregnancies with polyhydramnios were analysed. In 248 of the 537 pregnancies (46%) in this group there were no maternal complications or fetal malformations and the perinatal mortality (PNM) rate was 2.4%. The PNM rate increased significantly to 13.1% when there was associated pre-eclampsia, 10% with gestational diabetes, and to 7.6% with miscellaneous complications. When polyhydramnios was associated with a fetal or placental malformation the PNM rate was 61.4%. The commonest malformations were central nervous system (31%), musculoskeletal (12%) and gastrointestinal system anomalies (10%). Placental chorioangioma occurred in two patients (0.4%) and both babies died. In women with low oestriol excretion (18% of the 455 tested) the PNM rate increased five times to 22.7%.

Correlation between human placental lactogen levels and glucose metabolism in pregnant women with intrauterine growth retardation

Twenty pregnant women with fetal growth retardation and 20 pregnant women with appropriate for gestational age fetuses (controls) were recruited after the 28th week of gestation. Samples were collected for estimation of serum insulin and human placental lactogen (HPL) levels in the fasting state and a glucose tolerance test was carried out on all the subjects. The results showed the glucose and HPL levels to be significantly lower in the fetal growth retardation group compared to controls. There were no differences in the fasting serum insulin levels in the 2 groups. Fetal growth retardation appears to be linked with the absence of development of the physiological 'diabetogenic' state in the second half of pregnancy. This maternal hypoglycaemic state is associated with low HPL levels and not with raised maternal insulin levels as measured in the fasting state.

Preeclampsia in twin pregnancy--severity and pathogenesis

The incidence of preeclampsia in a consecutive series of 642 twin pregnancies was 25.9% compared with 9.7% in singleton pregnancies (p less than 0.001); in primiparas it was 35.2% and in multiparas 20.4% (p less than 0.001). Preeclampsia in twin pregnancies was more commonly of early onset (p less than 0.001) and the maternal disease more severe as assessed by the incidences of severe hypertension (p less than 0.001), proteinuria (p less than 0.004), and eclampsia (p less than 0.01). There were 1 maternal and 12 perinatal deaths. Oestriol excretion before the emergence of preeclampsia was lower in patients with severe compared with milder preeclampsia (p less than 0.05) as was plasma glucose concentration (p less than 0.05). Mean birth and placental weights according to gestation, tended to be lower in the severe group compared with uncomplicated cases and those with milder preeclampsia, as were also the placental-fetal weight ratios. The similarity of results with those already reported for singleton pregnancy suggested a similar pathogenesis for preeclampsia in twin and singleton pregnancies.

Antenatal pregnancy complications and fetal growth retardation

This study reports the associations between antenatal complications, subnormal urinary oestriol excretion and perinatal death in 500 pregnancies when the baby weighed less than the 10th centile for gestational age at birth, compared with those in a series of 500 pregnancies when the baby was of a normal weight for gestation. The overall incidence of antenatal complications was not higher in those pregnancies in which the fetus was growth retarded, although early onset pre-eclampsia, threatened abortion, diabetes mellitus and accidental haemorrhage were commoner (P less than 0.05). The incidence of subnormal urinary oestriol excretion was significantly higher in pregnancies in which the fetus was growth retarded, both when other antenatal complications were present (54.7% in the study group, 18.4% in the control group P less than 0.001) and in uncomplicated pregnancies (37.7% and 13.3%, respectively, P less than 0.001). Subnormal oestriol excretion identified 20 of the 26 perinatal deaths in the growth retardation group and 4 of the 6 perinatal deaths in the control group. Perinatal mortality was 10 times higher in growth retarded infants than in infants of appropriate size for gestation when pregnancy was not complicated antenatally. This study confirms the need to identify the presence of fetal growth retardation antenatally to enable appropriate treatment and improvement in perinatal mortality. The presence of antenatal complications is not appropriate for identification, whilst subnormal urinary oestriol excretion was seen to have highly significant predictive value.

The glucose tolerance test as a means of identifying intrauterine growth retardation

The purpose of this prospective, nonconcurrent study was to determine whether maternal hypoglycemia, as measured by a 3-hour glucose tolerance test, is associated with pregnancies resulting in growth-retarded infants. Our results demonstrate that maternal hypoglycemia is significantly associated with intrauterine growth retardation other than the low birth weight type and that the 3-hour glucose tolerance test is an effective early screening test in detecting pregnancies at risk of fetal growth retardation.

Glycosylated haemoglobin in pregnancy

A study of the use of glycosylated haemoglobin (glyco Hb) levels to identify the pregnant woman with abnormal glucose tolerance and as an adjunct in the control of the diabetic pregnant patient was undertaken. There was no difference in glyco Hb levels in pregnant women with normal or abnormal glucose tolerance. Mean glyco Hb levels were found to increase with the progress of pregnancy. Serial estimations of glyco Hb level in diabetic pregnant women reflected the degree of overall control, but were inadequate, when compared with serial glucose estimations, to assess the often rapidly-changing requirements of pregnancy.

Fetal growth retardation and pre-eclampsia

In a series of 2434 patients with pre-eclampsia, the prevalence of fetal growth retardation was 8.7 per cent compared with 8.6 per cent in the total hospital population. The prevalence was increased in early-onset pre-eclampsia (18.2 per cent) (P less than 0.001) and reduced in late-onset pre-eclampsia (5.6 per cent) (P less than 0.001). In patients who later developed early-onset pre-eclampsia with fetal growth retardation, the prevalence of subnormal oestriol excretion was significantly increased (79.5 per cent) (P less than 0.001) as was the prevalence of hypoglycaemia (33.3 per cent) (P less than 0.001) suggesting that fetal growth retardation in these pregnancies preceded the clinical signs of pre-eclampsia. The prevalence of placental abruption (8.3 per cent) and the prevalence of perinatal deaths (28.7 per cent) were both significantly higher in pregnancies with early-onset pre-eclampsia and fetal growth retardation (P less than 0.001).

Fetal growth and placental function assessed by urinary estriol excretion before the onset of pre-eclampsia

In a series of 1,316 patients with pre-eclampsia 744 had urinary estriol excretion measured before and 366 after the onset of clinical signs of the disease. Low estriol excretion had a highly significant association with fetal growth retardation and perinatal death both before and after the onset of clinical signs (p less than 0.001). As assessed by the incidences of low estriol excretion, fetal growth retardation, and perinatal wastage, pre-eclampsia of early onset (before 37 weeks) was a malignant disease in comparison with pre-eclampsia of late onset (after 37 weeks). Patients destined to develop early-onset pre-eclampsia had a high incidence of subnormal estriol excretion (25.4%; p less than 0.001). Although further deterioration of placental function occurred after the onset of clinical signs (41.3%; p less than 0.01), fetal growth and prognosis were already determined.

The significance of abnormal glucose tolerance (hyperglycaemia and hypoglycaemia) in pregnancy

Maternal hypoglycaemia (plasma glucose below 5th centile) had a highly significant association with fetal growth retardation, and perinatal mortality was significantly increased in the presence of both hypoglycaemia and hyperglycaemia (plasma glucose above 95th centile) when pregnancy outcome was analyzed in 5000 consecutive patients who had a glucose tolerance test performed during the third trimester of pregnancy. This study confirms the significance of abnormal glucose tolerance as a causative factor of feto-placental dysfunction. The flat glucose tolerance test pattern had no significance beyond the presence of associated hypoglycaemia, but reactive hypoglycaemia, and persistent abnormalities of plasma glucose levels during the test, were associated with higher incidences of complicated outcome. Hypertonic dextrose therapy administered to the patient with persistently subnormal urinary oestriol excretion was less likely to cause a favourable response in oestriol excretion if glucose tolerance was abnormal, perhaps because the adverse influences of abnormal glucose tolerance were not reversible by the third trimester of pregnancy. Hypoglycaemia and hyperglycaemia, additional to diabetes mellitus, are significant factors in the aetiology and diagnosis of abnormal pregnancy, and point to the need to investigate therapeutic measures.

The recurrence rate and significance of low oestriol excretion in successive pregnancies

A total of 440 women who had low oestriol excretion in a previous pregnancy was investigated by urinary oestriol assays in one or more subsequent pregnancies. The incidence of low oestriol excretion in the subsequent pregnancy was 29.1 per cent, or more than double that in the total obstetric population (13.4 per cent; p less than 0.001). Patients with persistently low oestriol excretion had a 40.8 per cent recurrence rate in subsequent pregnancies. When oestriol excretion was low in successive pregnancies it retained a significant association with increased incidences of stillbirths, neonatal deaths and fetal growth retardation. It was concluded that low oestriol excretion in a previous pregnancy is a definite indication to test fetoplacental function in subsequent pregnancies even when the clinical findings are normal.

Importance of abnormal glucose tolerance (hypoglycaemia and hyperglycaemia) in the aetiology of pre-eclampsia

In a series of 794 patients who had glucose tolerance tests done before the onset of pre-eclampsia, both hypoglycaemia (less than 5th percentile) and hyperglycaemia (P less than 95th percentile) had a significant association with early-onset severe pre-eclampsia ( less than 0.05). In the total series of 794 patients, hypoglycaemia had a significant association with low oestriol excretion (p less than 0.01), fetal growth retardation (p less than 0-05), low Apgar score (p less than 0.05), and perinatal mortality (p less than 0.05). These data indicate that, in patients with pre-eclampsia, hypoglycaemia is directly related to the cause of perinatal death.