Glycosylated haemoglobin in normal pregnancy: a longitudinal study with two independent methods

Association between hemoglobin A1c trajectory during pregnancy and adverse birth outcomes among non-gestational diabetic women

AIMS

Previous studies have shown that higher hemoglobin A1c (HbA1c) levels within the normal range during pregnancy can increase the risk of adverse birth outcomes. However, the effects of the longitudinal HbA1c trajectory during pregnancy on adverse birth outcomes among non-gestational diabetic women are poorly characterized. We aimed to identify HbA1c trajectory during pregnancy among non-gestational diabetic women and to estimate their associations with adverse birth outcomes.

METHODS

Data was extracted from the Information System of Guangdong Women and Children Hospital, China, from January 2017 to July 2022. This study involved 13,979 women who did not have gestational diabetes mellitus and underwent repeated HbA1c measurements during pregnancy. Latent mixture modeling was used to identify HbA1c trajectory groups. Logistic regression was applied to explore the associations between HbA1c trajectory groups and adverse birth outcomes, including preterm delivery, low birth weight, macrosomia, small for gestational age, and large for gestational age (LGA).

RESULTS

Three HbA1c trajectory groups were identified: low-stable (range 4.0% [20 mmol/mol]-4.4% [25 mmol/mol]), moderate-stable (range 4.6% [27 mmol/mol]-5.1% [32 mmol/mol]), and elevated-increasing (range 5.0% [31 mmol/mol]-5.6% [38 mmol/mol]). Compared with the low-stable HbA1c group, the elevated-increasing group had a higher risk of preterm delivery and LGA. The adjusted OR (95% CIs) were 1.67 (1.13, 2.49) and 1.47 (1.01, 2.12) for preterm delivery and LGA, respectively.

CONCLUSIONS

Among non-gestational diabetic women, the elevated-increasing HbA1c trajectory group was associated with a higher risk of preterm delivery and LGA. This finding emphasizes the importance of maintaining optimal HbA1c levels throughout pregnancy.

Reference range for glycated haemoglobin in full term non diabetic pregnant women: a multicentric cross sectional study

BACKGROUND

There are no large studies to define the normal value of glycated haemoglobin (HbA1c) measured in full term pregnant women measured at the time of delivery.

RESEARCH DESIGN AND METHODS

The study was conducted at three government hospitals in South India. Clinical data, maternal blood sample and foetal cord blood sample were collected from women admitted for safe confinement. Mean (± SD) of HbA1c in participants with no known diabetes (gestational or pregestational) or any complications (maternal or fetal) is described, 2.5th-97.5th centile reference range was derived.

RESULTS

From 3 centres, 2004 women participated in the study. Data from 1039 participants who had no history of diabetes or any maternal or fetal complication were used to determine the reference range for HbA1c at term pregnancy. The mean HbA1c in subjects devoid of diabetes and its known complications was 5.0 (± 0.39) %. The reference range for normal HbA1c at term in these women was found to be 4.3-5.9%. Maternal HbA1c at term pregnancy in non-diabetic pregnant women is associated with pre-pregnancy BMI, maternal age and 2-h plasma glucose level of 2nd trimester oral glucose tolerance test (OGTT).

CONCLUSIONS

The mean HbA1c at term pregnancy in non-diabetic women admitted for safe confinement is 5.00 (± 0.39) %. An HbA1c of 5.9% or more at term should be considered abnormal and women with such a value may be kept at a close surveillance for development of diabetes.

Hemoglobin A1c as a Substitute for Oral Glucose Testing in Early Pregnancy Screening

OBJECTIVE

Current recommendations for individuals with risk factors for gestational diabetes mellitus (GDM) call for screening in early pregnancy. However, there is currently no clear consensus on a specific screening modality. This study evaluates whether a hemoglobin A1c (HbA1c) screening in individuals with risk factors for gestational diabetes (GDM) could be used instead of an early 1-hour glucose challenge test (GCT). We hypothesized that the HbA1c could replace 1-hour GCT in early pregnancy evaluation STUDY DESIGN:  This is a prospective observational trial at a single tertiary referral center of women with at least one risk factor for GDM who were screened at <16 weeks of gestation with both 1-hour GCT or HbA1c. Exclusion criteria include: previous diagnosis of diabetes mellitus, multiple gestation, miscarriage, or missing delivery information. The diagnosis of GDM was made by a 3-hour 100-g glucose tolerance test, using the Carpenter-Coustan criteria (at least two results >94, 179, 154, and 139 mg/dL for fasting, 1-, 2-, and 3-hour values, respectively), 1-hour GCT > 200 mg/dL, or HbA1c > 6.5%.

RESULTS

A total of 758 patients met inclusion criteria. A total of 566 completed a 1-hour GCT and 729 had an HbA1c collected. The median gestational age at testing was 91/7 weeks (range: 40/7-156/7 weeks]. Twenty-one participants were diagnosed with GDM at <16 weeks' GA. The receiver operating characteristic (ROC) curves identified the optimal valves for a positive screen for an HbA1c > 5.6%. The HbA1c had a sensitivity of 84.2%, a specificity of 83.3%, and a false positive rate of 16.7% (p < 0.001). The area under the ROC curve for the HbA1c was 0.898. Gestational age of delivery was slightly earlier with individuals with an elevated HbA1c but no other changes in delivery or neonatal outcomes. Contingent screening improved specificity (97.7%) and decreased false positive rate to 4.4%.

CONCLUSION

HbA1c may be a good assessment in early pregnancy for gestational diabetes.

KEY POINTS

· HbA1c is a rational assessment in early pregnancy.. · An HbA1c > 5.6% is associated with gestational diabetes.. · Contingent screening limits the need for additional testing..

A pregnancy-specific Glucose management indicator derived from continuous glucose monitoring in pregnant women with type 1 diabetes

OBJECTIVE

Glucose management indicator (GMI) is a core metric derived from continuous glucose monitoring (CGM) and is widely used to evaluate glucose control in patients with diabetes. No study has explored the pregnancy-specific GMI. This study aimed to derive a best-fitting model to calculate GMI from mean blood glucose (MBG) obtained from CGM among pregnant women with type 1 diabetes mellitus (T1DM).

METHODS

A total of 272 CGM data and corresponding laboratory HbA1c from 98 pregnant women with T1DM in the CARNATION study were analysed in this study. Continuous glucose monitoring data were collected to calculate MBG, time-in-range (TIR), and glycaemic variability parameters. The relationships between the MBG and HbA1c during pregnancy and postpartum were explored. Mix-effect regression analysis with polynomial terms and cross-validation method was conducted to investigate the best-fitting model to calculate GMI from MBG obtained by CGM.

RESULTS

The pregnant women had a mean age of 28.9 ± 3.8 years, with a diabetes duration of 8.8 ± 6.2 years and a mean body mass index (BMI) of 21.1 ± 2.5 kg/m2 . The HbA1c levels were 6.1 ± 1.0% and 6.4 ± 1.0% during pregnancy and at postpartum (p = 0.024). The MBG levels were lower during pregnancy than those at postpartum (6.5 ± 1.1 mmol/L vs. 7.1 ± 1.5 mmol/L, p = 0.008). After adjusting the confounders of haemoglobin (Hb), BMI, trimesters, disease duration, mean amplitude of glycaemic excursions and CV%, we developed a pregnancy-specific GMI-MBG equation: GMI for pregnancy (%) = 0.84-0.28* [Trimester] + 0.08 * [ BMI in kg/m2 ] + 0.01 * [Hb in g/mL] + 0.50 * [MBG in mmol/L].

CONCLUSIONS

We derived a pregnancy-specific GMI equation, which should be recommended for antenatal clinical care.

CLINICAL TRIAL REGISTRY NUMBER

ChiCTR1900025955.

Determination of Time in Range Associated with HbA1c ≤6.5% in Latin American pregnant women diagnosed with type 1 diabetes mellitus using an automated insulin delivery system

AIMS

To determine the correlation between %TIR and HbA1c in pregnant women with type 1 diabetes mellitus (DM1).

METHODS

Diagnostic test study in a prospective cohort of pregnant patients with DM1 using automated insulin delivery system (AID)in Colombia and Chile.

RESULTS

Fifty-two patients were included [mean age 31.8±6.2 years, pregestational HbA1c 7.2% [interquartile range (IQR), 6.5-8.2]. During follow-up, we found a better metabolic control during the second (HbA1c 6.40%, IQR 5.9,7.1) and third trimesters (HbA1c 6.25%;IQR 5.9,6.8). A weak and negative correlation between %TIR and HbA1c was found for all the gestation (Spearman's rank correlation coefficient:-0.22, p:0.0329), and in the second (r :-0.13, p: 0.38) and third trimesters (r:-0.26, p=0.08). %TIR had poor discriminating capacity for predicting HbA1c <6% (area under the curve [AUC], 0.59; 95% confidence interval [CI],0.46-0.72) and for predicting HbA1c <6.5% (AUC, 0.57;95% CI,0.44-0.70). The optimal cutoff points for %TIR were >66.1% for predicting HbA1c <6% (65% sensitivity, 62% specificity) and %TIR >61.1% for HbA1c <6.5% (59% sensitivity, 54% specificity).

CONCLUSION

The correlation between HbA1c and %TIR during pregnancy was weak. The optimal cutoff points for identifying patients with HbA1c <6.0% and <6.5% were %TIR >66.1% and >61.1%, respectively, with moderate sensitivity and specificity.

Establishing Trimester-Specific Haemoglobin A1c Reference Intervals in Pregnant Women: A retrospective study of healthy South Asian women with normal pregnancy outcomes

Objectives

This study aimed to define trimester-specific haemoglobin A1c (HbA1c) reference intervals in healthy, pregnant South Asian women.

Methods

This retrospective study was conducted at St. Stephen's Hospital, Delhi, India, between January 2011 and December 2016. Healthy pregnant women were compared to a control group of healthy non-pregnant women. Pregnant participants had term deliveries of babies with appropriate gestational weights. The HbA1c levels were calculated in terms of non-parametric 2.5 and 97.5 percentiles for women in first (T1), second (T2) and third (T3) trimester groups. Statistical tests were used to obtain the normal HbA1c reference values and were considered significant when P <0.05.

Results

This study included a total of 1,357 healthy pregnant women and a control group of 67 healthy, non-pregnant women. Pregnant women had a median HbA1c of 4.8% (4-5.5%) or 32 mmol/mol (20-39 mmol/mol); non-pregnant women had a median HbA1c of 5.1% (4-5.7%) or 29 mmol/mol (20-37 mmol/mol; P <0.001). The HbA1c levels for the T1, T2 and T3 groups were 4.9% (4.1-5.5%) or 30 mmol/mol (21-37 mmol/mol), 4.8% (4.5-5.3%) or 29 mmol/mol (20-34 mmol/mol) and 4.8% (3.9-5.6%) or 29 mmol/mol (19-38 mmol/mol), respectively. The HbA1c values were significant when comparing T1 versus T2 (P <0.001), T1 versus T3 (P = 0.002) and T1 versus the non-pregnant group (P = 0.001). However, T2 versus T3 was not significant (P = 0.111).

Conclusion

Compared to non-pregnant women, HbA1c levels were lower in pregnant women, despite women in the T2 and T3 groups having a higher body mass index than the women in the T1 and non-pregnant groups. Further research is recommended to understand the factors responsible and validate these findings.

Relationship of anthropometric measurements with glycated hemoglobin and 1-h blood glucose after 50 g glucose challenge test in pregnant women: A longitudinal cohort study in Southern Thailand

AIMS

To assess correlations of anthropometric measurements with glycated hemoglobin (HbA1c) and 1-h blood glucose after a 50 g glucose challenge test during the first and late second trimesters and explore their relationships of anthropometric measurements with neonatal birth weight.

METHODS

A longitudinal study was conducted among pregnant Thai women with gestational age ≤14 weeks. Anthropometric measurements, using body mass index, body compositions, and circumferences, and skinfold thickness, were measured at four-time points: ≤14, 18-22, 24-28, and 30-34 weeks of gestation. HbA1c and 1-h blood glucose were examined at ≤14 and 24-28 weeks. Neonatal birth weight was recorded.

RESULTS

Of 312 women, HbA1c was more correlated with anthropometric measurements during pregnancy than 1-h blood glucose. At 24-28 weeks, women with high/very high body fat percentage were more likely to have higher HbA1c. Women with high subscapular skinfold thickness were more likely to have higher 1-h blood glucose at ≤14 and 24-28 weeks. High hip circumference significantly increased neonatal birth weights.

CONCLUSION

Anthropometric measurements were longitudinally correlated with HbA1c and 1-h blood glucose, higher in the late second than first trimesters, as well as neonatal birth weight. The mechanisms to explain the relationship of different anthropometric measurements are required to be further studied.

Early Gestational Diabetes Mellitus: Diagnostic Strategies and Clinical Implications

Preexisting diabetes mellitus (DM) should be ruled out early in pregnancy in those at risk. During screening, a significant proportion of women do not reach the threshold for overt DM but fulfill the criteria used for diagnosing conventional gestational DM (cGDM). There is no consensus on the management of pregnancies with intermediate levels of hyperglycemia thus diagnosed. We have used the term early gestational DM (eGDM) for this condition and reviewed the currently available literature. Fasting plasma glucose (FPG), oral glucose tolerance test, and glycated hemoglobin (HbA1c) are the commonly employed screening tools in early pregnancy. Observational studies suggest that early pregnancy FPG and Hba1c correlate with the risk of cGDM and adverse perinatal outcomes. However, specific cut-offs, including those proposed by the International Association of the Diabetes and Pregnancy Study Group, do not reliably predict the development of cGDM. Emerging data, though indicate that FPG ≥ 92 mg/dL (5.1 mmol/L), even in the absence of cGDM, signals the risk for perinatal complication. Elevated HbA1c, especially a level ≥ 5.9%, also correlates with the risk of cGDM and worsened outcome. HbA1c as a diagnostic test is however besieged with the usual caveats that occur in pregnancy. The studies that explored the effects of intervention present conflicting results, including a possibility of fetal malnutrition and small-for-date baby in the early treatment group. Diagnostic thresholds and glycemic targets in eGDM may differ, and large multicenter randomized controlled trials are necessary to define the appropriate strategy.

COVID-19 pandemic: Can fasting plasma glucose and HbA1c replace the oral glucose tolerance test to screen for hyperglycaemia in pregnancy?

AIMS

To evaluate proposals considering HbA1c and fasting plasma glucose (FPG) measurement as a substitute for oral glucose tolerance test (OGTT) to diagnose hyperglycaemia in pregnancy (HIP) during COVID-19 pandemic.

METHODS

Of the 7,334 women who underwent the OGTT between 22 and 30 weeks gestation, 966 had HIP (WHO diagnostic criteria, reference standard). The 467 women who had an available HbA1c were used for analysis. French-speaking Society of Diabetes (SFD) proposal to diagnose HIP during COVID-19 pandemic was retrospectively applied: HbA1c ≥5.7% (39 mmol/mol) and/or FPG level ≥5.1 mmol/l. SFD proposal sensitivity for HIP diagnosis and the occurrence of HIP-related events (preeclampsia, large for gestational age infant, shoulder dystocia or neonatal hypoglycaemia) in women with false negative (FN) and true positive (TP) HIP-diagnoses were evaluated.

RESULTS

The sensitivity was 57% [95% confidence interval 52-62]. FN women had globally lower plasma glucose levels during OGTT, lower HbA1c and body mass index than those TP. The percentage of HIP-related events was similar in FN (who were cared) and TP cases, respectively 19.5 and 16.9% (p = 0.48). We observed similar results when women at high risk for HIP only were considered.

CONCLUSION

The SFD proposal has a poor sensitivity to detect HIP. Furthermore, it fails to have any advantages in predicting adverse outcomes.

Role of maternal glucose metabolism in the association between maternal BMI and neonatal size and adiposity

BACKGROUND/OBJECTIVE

One potential mechanism by which maternal obesity impacts fetal growth is through hyperglycemia below the threshold for gestational diabetes. Data regarding which measures of maternal glucose metabolism mediate this association is sparse. The objectives of this study were to (i) quantify the associations of maternal pre-pregnancy body mass index (BMI) with neonatal size and adiposity and (ii) examine the role of markers of maternal glucose metabolism as mediators in these associations.

SUBJECTS/METHODS

This is a secondary analysis of 6,379 mother-infant dyads from the Hyperglycemia and Adverse Pregnancy Outcome cohort. Markers of glucose metabolism, including plasma glucose and c-peptide values, Stumvoll first-phase estimate, modified Matsuda index, and oral disposition index were measured and calculated from an oral glucose tolerance test (OGTT) between 24- and 32-weeks' gestation. We calculated the direct effect of maternal BMI category, measured at the time of the OGTT and regressed to estimate pre-pregnancy BMI, on neonatal (1) birth weight (BW), (2) fat mass (FM), (3) % body fat (BF%), and (4) sum of skinfold thickness (sSFT). We then calculated the indirect effect of BMI category on these measures through markers of glucose metabolism.

RESULTS

Maternal BMI category was positively associated with neonatal BW, FM, BF%, and sSFT. Additionally, mothers who were overweight or obese had higher odds of delivering an infant with BW, FM, BF%, or sSFT >90th percentile. Fasting glucose and c-peptide values were the strongest mediators in the linear associations between maternal BMI category and neonatal size and adiposity.

CONCLUSIONS

Maternal overweight and obesity were associated with higher odds of neonatal BW and adiposity >90th percentile. Fasting measures of glucose metabolism were the strongest mediators of these associations, suggesting that future studies should investigate whether incorporation of these markers in pregnant women with obesity may improve prediction of neonatal size and adiposity.

Longitudinal Changes in the Relationship Between Hemoglobin A1c and Glucose Tolerance Across Pregnancy and Postpartum

OBJECTIVE

To characterize the relationship between hemoglobin A1c (HbA1c) levels and glucose tolerance across pregnancy and postpartum.

DESIGN AND PARTICIPANTS

In a longitudinal study of pregnant women with gestational diabetes risk factors (N = 102), we performed oral glucose tolerance testing (OGTT) and HbA1c measurements at 10-15 weeks of gestation, 24-30 weeks of gestation (N = 73), and 6-24 weeks postpartum (N = 42). Complete blood counts were obtained from clinical records. We calculated HbA1c-estimated average glucose levels and compared them with mean OGTT glucose levels (average of fasting, 1- and 2-hour glucose levels). Linear mixed effects models were used to test for longitudinal changes in measurements.

RESULTS

Mean OGTT glucose increased between 10-15 and 24-30 weeks of gestation (β = 8.1 mg/dL, P = .001), while HbA1c decreased during the same time period (β = -0.13%, P < .001). At 10-15 weeks of gestation and postpartum the discrepancy between mean OGTT glucose and HbA1c-estimated average glucose was minimal (mean [standard deviation]: 1.2 [20.5] mg/dL and 0.16 [18.1] mg/dL). At 24-30 weeks of gestation, the discrepancy widened (13.2 [17.9] mg/dL, β = 12.7 mg/dL, P < .001, compared to 10-15 weeks of gestation, with mean OGTT glucose being higher than HbA1c-estimated average glucose). Lower hemoglobin at 24-30 weeks of gestation was associated with a greater discrepancy (β = 6.4 mg/dL per 1 g/dL lower hemoglobin, P = .03 in an age- and gestational age-adjusted linear regression model).

CONCLUSIONS

HbA1c accurately reflects glycemia in the 1st trimester, but underestimates glucose intolerance in the late 2nd trimester. Lower hemoglobin level is associated with greater underestimation. Accounting for gestational age and maternal hemoglobin may improve the clinical interpretation of HbA1c levels during pregnancy.

Maternal serum glycosylated hemoglobin and fasting plasma glucose predicts gestational diabetes at the first trimester in Turkish women with a low-risk pregnancy and its relationship with fetal birth weight; a retrospective cohort study

OBJECTIVE

To examine the accuracy of maternal serum glycosylated hemoglobin (HbA1c) and fasting plasma glucose (FPG) levels in predicting gestational diabetes at the first trimester in Turkish women with a low-risk pregnancy and its relationship with fetal birth weight.

METHODS

This cohort study was conducted retrospectively in a tertiary referral hospital from January 2010 to January 2017. HbA1c and FPG serum concentrations were measured in 670 pregnant women at the first-trimester screening. HbA1c and FPG concentrations of women who subsequently developed gestational diabetes mellitus (GDM) were compared to those who did not, and its relationship with fetal weight was investigated.

RESULTS

First-trimester screening was performed on 608 pregnant women, of whom 69 (11.3%) women had developed GDM. Median HbA1c and FPG concentrations were significantly higher in women developing GDM (n = 69) in comparison to those with uncomplicated pregnancies (n = 539) (5.31 ± 0.58% versus 5.01 ± 0.45%, p < .001 and 89.74 ± 8.71% versus 84.09 ± 9.16%, p < .001, respectively). The cut-off value calculated with the highest Youden index was HbA1c levels above 5.6% with a sensitivity of 34.78%, specificity of 89.8%, with a diagnostic accuracy of 83.55%, and FPG levels above 86.85 mg/dl with a sensitivity of 69.57%, specificity of 61.78%, with a diagnostic accuracy of 62.66%. The calculated odds ratio (OR) for HbA1c > 5.6% and FPG > 86 mg/dl were 4.69 (95% CI: 2.66-8.29), and 3.7 (95% CI: 2.15-6.35), respectively. HbA1c and FPG combined had improved the predictive capability for GDM (OR: 7.26, 95% CI: 3.71-14.19). According to correlation analyses, a noteworthy positive correlation was found between HbA1c and, FPG, 50 g GCT, age, BMI, parity, and birth weight. However, there was no correlation between FPG and birth weight.

CONCLUSION

Diagnostic accuracy of HbA1c for GDM prediction in Turkish women with a low-risk pregnancy is 83.55% with a very good negative predictive value of 91.49%. HbA1c and FPG combined enhanced the predictive capability for GDM. In addition, there is a positive relationship between HbA1c and 50 g GCT, and birth weight. However, to suggest HbA1c as a potential screening test for gestational diabetes mellitus, further research is warranted.

Reference intervals for hemoglobin A1c (HbA1c) in healthy Mexican pregnant women: a cross-sectional study

BACKGROUND

The reference intervals for hemoglobin A1c (HbA1c) in pregnant Mexican women without diabetes are not well defined. The study aims to determine the reference intervals for HbA1c at each trimester in healthy Mexican pregnant women.

METHODS

This cross-sectional study included healthy Mexican pregnant women in trimester 1 (T1), 6-13.6 weeks of gestation (WG), trimester 2 (T2), 14-27 WG, and trimester 3 (T3), ≥27-36 WG, with a maternal age > 18 years, and pregestational body mass index (BMI) ranging between 18.5-24.9 kg/m2. Women with gestational diabetes mellitus, pregestational diabetes, anemia, a pregestational BMI < 18.5 or ≥ 25 kg/m2, and any hematologic, hepatic, immunological, renal, or cardiac disease were excluded. HbA1c was measured using high-performance liquid chromatography based on the National Glycohemoglobin Standardization Program-certified PDQ Primus guidelines. The HbA1c reference intervals were calculated in terms of the 2.5th to the 97.5th percentiles.

RESULTS

We analyzed the HbA1c values of 725 women (T1 n = 84, T2 n = 448, and T3 n = 193). The characteristics of the participants were expressed as mean ± standard deviation and included: maternal age (28.2 ± 6.7 years), pregestational weight (54.8 ± 5.9 Kg), pregestational BMI (22.2 ± 1.7 Kg/m2), and glucose values using a 75 g-2 h oral glucose tolerance test; fasting 4.5 ± 0.3 mmol/L (81.5 ± 5.5 mg/dL), 1 h 6.4 ± 1.5 mmol/L (115.3 ± 26.6 mg/dL), and 2 h 5.7 ± 1.1 mmol/L (103.5 ± 19.6 mg/dL). Reference intervals for HbA1c, expressed as median and 2.5th to 97.5th percentile for each trimester were: T1: 5.1 (4.5-5.6%), T2: 5.0 (4.4-5.5%), and T3: 5.1 (4.5-5.6%).

CONCLUSIONS

The reference range of HbA1C in healthy Mexican pregnant women during pregnancy was 4.4% to 5.6%. We suggest as upper limits of HbA1c value ≤5.6%, 5.5%, and 5.7% for T1, T2, and T3, respectively among Mexican pregnant women.

Beyond self-monitored plasma glucose and HbA1c: the role of non-traditional glycaemic markers in gestational diabetes mellitus

Strict glycaemic management is the cornerstone of metabolic control in gestational diabetes mellitus (GDM). Current monitoring standards involve self-monitoring plasma glucose (SMBG) and haemoglobin A1c (HbA1c). However, both have important limitations. SMBG only reflects instantaneous blood glucose and the inconvenience of self-collecting blood frequently results in poor compliance. HbA1c provides information on blood glucose levels from the previous 2 to 3 months and it is influenced by iron-deficient states, common during pregnancy. There is an urgent need for new shorter-term glycaemic markers, as glycated albumin, fructosamine or 1,5-anhydroglucitol. Glycated albumin seems especially interesting as it provides information on blood glucose levels over the foregoing 2-3 weeks and it is not influenced by iron deficiency or the dilutional anaemia of pregnancy. Fructosamine has a precise and inexpensive measurement and it is not affected by haemoglobin characteristics. This review further discusses the potential value of these non-traditional indicators of glycaemic control in patients with GDM, outlining their possible future applications.

Comparison of HbA1c and glycated albumin as a control marker for newborn complications in diabetic women in a multicentre study in Japan (Japan glycated albumin study group: study 2)

Background

To clarify the relationship between glycated haemoglobin and glycated albumin concentrations during pregnancy with neonatal outcomes, a multicentre study was conducted by the Japanese Society of Diabetes and Pregnancy.

Methods

A total of 136 patients (type 1: n = 47, type 2: n = 89) who enrolled in the study were diagnosed based on the Japanese Diabetes Society diagnostic criteria for diabetes mellitus. Thresholds for glycated haemoglobin and glycated albumin were set at 5.8% and 15.8%, respectively, as the upper limits of the reference interval in pregnant women.

Result

Random plasma glucose decreased linearly, and reached the reference interval at 40 weeks. Glycated albumin concentrations also decreased in the same manner. But glycated haemoglobin concentrations were out of the reference interval during the study. The frequency of the neonatal complications did not show significant differences between the glycated haemoglobin ⩾5.8% group and the glycated haemoglobin <5.8% group. On the other hand, the frequency of neonatal complications showed higher tendency of neonatal complications in the incidence of polycythaemia ( P = 0.094) and heavy-for-date ( P = 0.071) in the glycated albumin ⩾15.8% group compared with the glycated albumin <15.8 group. The respiratory disorder in type 1 diabetes was significantly higher than type 2 diabetes.

Conclusions

For the treatment of pregnant women with diabetes, glycated albumin would be a better marker than glycated haemoglobin. However, glycated albumin is also affected by obesity and albumin, and it is desirable to make a comprehensive judgment with glycated haemoglobin, random plasma glucose and other glycaemic index.

Emerging Technologies for the Management of Type 1 Diabetes in Pregnancy

PURPOSE OF REVIEW

The purpose of the study is to discuss emerging technologies available in the management of type 1 diabetes in pregnancy.

RECENT FINDINGS

The latest evidence suggests that continuous glucose monitoring (CGM) should be offered to all women on intensive insulin therapy in early pregnancy. Studies have additionally demonstrated the ability of CGM to help gain insight into specific glucose profiles as they relate to glycaemic targets and pregnancy outcomes. Despite new studies comparing insulin pump therapy to multiple daily injections, its effectiveness in improving glucose and pregnancy outcomes remains unclear. Sensor-integrated insulin delivery (also called artificial pancreas or closed-loop insulin delivery) in pregnancy has been demonstrated to improve time in target and performs well despite the changing insulin demands of pregnancy. Emerging technologies show promise in the management of type 1 diabetes in pregnancy; however, research must continue to keep up as technology advances. Further research is needed to clarify the role technology can play in optimising glucose control before and during pregnancy as well as to understand which women are candidates for sensor-integrated insulin delivery.

Serum Malondialdehyde Concentration and Glutathione Peroxidase Activity in a Longitudinal Study of Gestational Diabetes

Aims

The main goal of this study was to evaluate the presence of oxidative damage and to quantify its level in gestational diabetes.

Methods

Thirty-six healthy women and thirty-six women with gestational diabetes were studied in the three trimesters of pregnancy regarding their levels of oxidative stress markers. These women were diagnosed with diabetes in the second trimester of pregnancy. Blood glucose levels after 100g glucose tolerance test were higher than 190, 165 or 145 mg/dl, 1, 2 or 3 hours after glucose intake.

Results

The group of women with gestational diabetes had higher serum malondialdehyde levels, with significant differences between groups in the first and second trimester. The mean values of serum glutathione peroxidase activity in the diabetic women were significantly lower in the first trimester. In the group of women with gestational diabetes there was a negative linear correlation between serum malondialdehyde concentration and glutathione peroxidase activity in the second and third trimester.

Conclusions

In this observational and longitudinal study in pregnant women, the alterations attributable to oxidative stress were present before the biochemical detection of the HbA1c increase. Usual recommendations once GD is detected (adequate metabolic control, as well as any other normally proposed to these patients) lowered the concentration of malondialdehyde at the end of pregnancy to the same levels of the healthy controls. Serum glutathione peroxidase activity in women with gestational diabetes increased during the gestational period.

Is There a Role for HbA1c in Pregnancy?

Outside pregnancy, HbA1c analysis is used for monitoring, screening for and diagnosing diabetes and prediabetes. During pregnancy, the role for HbA1c analysis is not yet established. Physiological changes lower HbA1c levels, and pregnancy-specific reference ranges may need to be recognised. Other factors that influence HbA1c are also important to consider, particularly since emerging data suggest that, in early pregnancy, HbA1c elevations close to the reference range may both identify women with underlying hyperglycaemia and be associated with adverse pregnancy outcomes. In later pregnancy, HbA1c analysis is less useful than an oral glucose tolerance test (OGTT) at detecting gestational diabetes. Postpartum, HbA1c analysis detects fewer women with abnormal glucose tolerance than an OGTT, but the ease of testing may improve follow-up rates and combining HbA1c analysis with fasting plasma glucose or waist circumference may improve detection rates. This article discusses the relevance of HbA1c testing at different stages of pregnancy.

Glycated Serum Albumin and AGE Receptors

In vivo modification of proteins by molecules with reactive carbonyl groups leads to intermediate and advanced glycation end products (AGE). Glucose is a significant glycation reagent due to its high physiological concentration and poorly controlled diabetics show increased albumin glycation. Increased levels of glycated and AGE-modified albumin have been linked to diabetic complications, neurodegeneration, and vascular disease. This review discusses glycated albumin formation, structural consequences of albumin glycation on drug binding, removal of circulating AGE by several scavenger receptors, as well as AGE-induced proinflammatory signaling through activation of the receptor for AGE. Analytical methods for quantitative detection of protein glycation and AGE formation are compared. Finally, the use of glycated albumin as a novel clinical marker to monitor glycemic control is discussed and compared to glycated hemoglobin (HbA1c) as long-term indicator of glycemic status.

An early pregnancy HbA1c ≥5.9% (41 mmol/mol) is optimal for detecting diabetes and identifies women at increased risk of adverse pregnancy outcomes

OBJECTIVE

Pregnant women with undiagnosed diabetes are a high-risk group that may benefit from early intervention. Extrapolating from nonpregnancy data, HbA1c ≥6.5% (48 mmol/mol) is recommended to define diabetes in pregnancy. Our aims were to determine the optimal HbA1c threshold for detecting diabetes in early pregnancy as defined by an early oral glucose tolerance test (OGTT) at <20 weeks' gestation and to examine pregnancy outcomes relating to this threshold.

RESEARCH DESIGN AND METHODS

During 2008-2010 in Christchurch, New Zealand, women were offered an HbA1c measurement with their first antenatal bloods. Pregnancy outcome data were collected. A subset completed an early OGTT, and HbA1c performance was assessed using World Health Organization criteria.

RESULTS

HbA1c was measured at a median 47 days' gestation in 16,122 women. Of those invited, 974/4,201 (23%) undertook an early OGTT. In this subset, HbA1c ≥5.9% (41 mmol/mol) captured all 15 cases of diabetes, 7 with HbA1c <6.5% (<48 mmol/mol). This HbA1c threshold was also 98.4% (95% CI 97-99.9%) specific for gestational diabetes mellitus (GDM) before 20 weeks (positive predictive value = 52.9%). In the total cohort, excluding women referred for GDM management, women with HbA1c of 5.9-6.4% (41-46 mmol/mol; n = 200) had poorer pregnancy outcomes than those with HbA1c <5.9% (<41 mmol/mol; n = 8,174): relative risk (95% CI) of major congenital anomaly was 2.67 (1.28-5.53), preeclampsia was 2.42 (1.34-4.38), shoulder dystocia was 2.47 (1.05-5.85), and perinatal death was 3.96 (1.54-10.16).

CONCLUSIONS

HbA1c measurements were readily performed in contrast to the low uptake of early OGTTs. HbA1c ≥5.9% (≥41 mmol/mol) identified all women with diabetes and a group at significantly increased risk of adverse pregnancy outcomes.

1,5-Anhydroglucitol and glycated albumin in glycemia

The main purpose of treating diabetes is to prevent the onset and the progression of diabetic chronic complications. Since the mechanism of onset of chronic complications is still not well understood, the main strategy to achieve this purpose is to bring the plasma glucose level in diabetic patients as close as possible to that in healthy subjects and try to maintain good glycemic control over the long term. Glycated hemoglobin (HbA1c), glycated albumin (GA), fructosamine, and 1,5-anhydroglucitol (1,5 AG) are used for evaluating glycemic control. At present, HbA1c is widely used as a gold standard index for glycemic control in clinical practice. While HbA1c reflects the long-term glycemic control state (for the past 1-2 months), it does not accurately reflect glycemic control in the clinical state in which glycemic control improves or deteriorates in the short-term. It is also known that HbA1c in patients with hematological disorders such as anemia and variant hemoglobin shows an abnormal value. In addition, HbA1c mainly reflects the mean plasma glucose but does not reflect the postprandial plasma glucose. On the other hand, GA and 1,5-AG reflect intermediate- or short-term glycemic control and are not influenced by hemoglobin metabolism. While 1,5-AG is known to reflect the postprandial plasma glucose, it was shown recently that GA also reflects the postprandial plasma glucose. This chapter summarizes the measurement methods, usage methods, evidence, and problems concerning such indices for glycemic control.

Glycated albumin; clinical usefulness

The main purpose of treating diabetes is to prevent the onset and progression of diabetic chronic complications. Since the mechanism of onset of chronic complications is still not well understood, the main strategy to achieve this purpose is to bring plasma glucose levels as close as possible to those in healthy subjects and maintain good glycemic control over the long term. Since glycation among various proteins is increased in diabetic patients compared with non-diabetic subjects, glycated protein can be used as a glycemic control indicator. Currently, among these glycated proteins, HbA1c is used as the gold standard of glycemic control indicators. However, HbA1c does not accurately reflect the actual status of glycemic control in some conditions with rapid changes in glycemic control and in patients with anemia (hemolytic anemia, iron deficiency anemia, etc.) and variant hemoglobin. In comparison, glycated albumin (GA) more accurately reflects changes in plasma glucose during the short term and postprandial plasma glucose. GA also reflects glycemic control in patients with hematologic disorders whereas GA does not reflect glycemic control in patients with disorder of albumin metabolism. GA is a glycemic control indicator which overcomes most of the disadvantages of HbA1c, and could be therefore expected to replace HbA1c as the standard glycemic control indicator in the near future. However, it is necessary to accumulate more evidences from large research studies on the effective directions for measuring GA.

A1C but not serum glycated albumin is elevated because of iron deficiency in late pregnancy in diabetic women

OBJECTIVE We have already reported that A1C is elevated because of iron deficiency in late pregnancy among nondiabetic pregnant women. This report examined whether the same phenomenon is observed in pregnant women with diabetes. RESEARCH DESIGN AND METHODS This longitudinal study was conducted in 17 pregnant women with diabetes (20-35 weeks of pregnancy). A1C, serum glycated albumin, erythrocyte indexes, and iron metabolism indexes were measured. RESULTS A1C levels were significantly increased in late pregnancy, whereas serum glycated albumin showed no significant changes. Glycated albumin/A1C ratio, mean corpuscular hemoglobin, serum transferrin saturation, and serum ferritin were significantly decreased in late pregnancy. Serum transferrin saturation showed a significant positive correlation with glycated albumin/A1C ratio. CONCLUSIONS A1C levels, but not serum glycated albumin levels, are elevated in late pregnancy because of iron deficiency in diabetic women. Serum glycated albumin may offer an adequate marker for glycemic control during pregnancy.

A1C but not serum glycated albumin is elevated in late pregnancy owing to iron deficiency

OBJECTIVE

A1C levels have been shown to be elevated in relation to glycemia in late pregnancy, although the precise mechanisms remain undetermined. We hypothesized that iron deficiency is involved in the A1C increase in late pregnancy.

RESEARCH DESIGN AND METHODS

In study 1, A1C, serum glycated albumin, erythrocyte indexes, and iron metabolism indexes were determined in 47 nondiabetic pregnant women not receiving iron supplementation who were divided into four groups according to gestational period (group I, 21-24 weeks; group II, 25-28 weeks; group III, 29-32 weeks; and group IV, 33-36 weeks). In study 2, these determinants were obtained at two gestational periods (20-23 weeks and 32-33 weeks) in 17 nondiabetic pregnant women.

RESULTS

In study 1, A1C levels were higher in groups III and IV than those in groups I and II, whereas serum glycated albumin levels were not different among these four groups. Hemoglobin, mean corpuscular hemoglobin (MCH), serum transferrin saturation, and serum ferritin were lower in groups III and IV. A1C levels were negatively correlated with MCH, serum transferrin saturation, and serum ferritin. In study 2, A1C levels were significantly increased at gestational weeks 32-33 from those at weeks 20-23, whereas serum glycated albumin levels did not differ between the two gestational periods. MCH, serum transferrin saturation, and serum ferritin were decreased at gestational weeks 32-33. A1C levels showed a negative correlation with MCH, serum transferrin saturation, and serum ferritin.

CONCLUSIONS

A1C levels were elevated in late pregnancy owing to iron deficiency. Serum glycated albumin may offer a better index for monitoring glycemic control in pregnancy.

Fetal pancreatic beta-cell function in pregnancies complicated by maternal diabetes mellitus: relationship to fetal acidemia and macrosomia

OBJECTIVE

Our purpose was to investigate the relationship between fetal pancreatic beta-cell function and fetal acidemia and macrosomia in pregnancies complicated by maternal diabetes mellitus.

STUDY DESIGN

A cross-sectional study at the Harris Birthright Research Centre for Fetal Medicine, London, was performed. In 32 pregnancies complicated by maternal diabetes mellitus cordocentesis was performed at 36 to 39 weeks' gestation for the measurement of umbilical venous blood pH, PO2, PCO2, lactate, and glucose concentration; plasma insulin immunoreactivity; and insulin/glucose ratio. A reference range for plasma insulin and insulin/glucose ratio was constructed by studying fetal blood samples from 80 women who did not have diabetes mellitus.

RESULTS

Mean umbilical venous blood pH was significantly lower and plasma insulin immunoreactivity and insulin/glucose ratio were significantly higher than the appropriate normal mean for gestation. There were significant associations between (1) maternal and fetal blood glucose concentrations (r = 0.95, p < 0.0001), (2) fetal blood glucose and plasma insulin immunoreactivity (r = 0.57, p < 0.01), (3) fetal plasma insulin immunoreactivity and blood pH (r = -0.39, p < 0.05), and (4) fetal insulin/glucose ratio and degree of macrosomia (r = 0.76, p < 0.0001).

CONCLUSION

Fetal pancreatic beta-cell hyperplasia is implicated in the pathogenesis of both fetal acidemia and macrosomia.

Placental and fetal Doppler velocimetry in pregnancies complicated by maternal diabetes mellitus

OBJECTIVE

Our purpose was to investigate placental and fetal circulation in pregnancies complicated by maternal diabetes mellitus and to relate any changes to fetal blood pH, Po2, and hematocrit.

STUDY DESIGN

Doppler measurements of both uterine arteries, one umbilical artery, the fetal descending thoracic aorta, and one fetal middle cerebral artery were performed in 65 well-controlled diabetic pregnancies in a cross-sectional study at the Harris Birthright Research Centre for Fetal Medicine, London. In 41 cases cordocentesis was also performed for the measurement of umbilical venous blood pH, Po2, and hematocrit.

RESULTS

The mean umbilical venous blood pH was significantly lower and the hematocrit significantly higher than the appropriate normal mean for gestation. However, the Doppler indices of the placental and fetal circulations were essentially normal, except in some of the cases complicated by preeclampsia or intrauterine growth retardation.

CONCLUSIONS

Maternal diabetes mellitus is not associated with abnormalities in Doppler indexes of the placental or fetal circulations.

Fetal plasma erythropoietin in pregnancies complicated by maternal diabetes mellitus

OBJECTIVE

Our purpose was to investigate the relationship between fetal plasma erythropoietin concentration and measures of short-term and long-term glycemic control and fetal oxygenation in pregnancies complicated by maternal diabetes mellitus.

STUDY DESIGN

A cross-sectional study was performed at The Harris Birthright Research Centre for Fetal Medicine, London. Cordocentesis was performed in 31 diabetic pregnancies for the measurement of umbilical venous blood pH, PO2, PCO2, lactate and glucose concentration, erythroblast count, hemoglobin, and plasma erythropoietin concentrations.

RESULTS

The mean pH was significantly lower and the PCO2, lactate, erythropoietin, hemoglobin, and erythroblast counts were significantly higher than the appropriate normal mean for gestation. There were significant associations between (1) fetal erythropoietin and erythroblast count, (2) fetal erythroblast count and hemoglobin, (3) fetal hemoglobin and maternal glycosylated hemoglobin, and (4) maternal glucose and fetal glucose, pH, and lactate.

CONCLUSIONS

We postulate that maternal hyperglycemia causes fetal hyperglycemia and acidemia. Increased erythropoietin may be caused by tissue hypoxia or hyperinsulinemia. The increase in fetal hemoglobin may be the consequence of increased erythropoiesis, mediated by either erythropoietin or hyperinsulinemia.

Glycated hemoglobin of fractionated erythrocytes, glycated albumin, and plasma fructosamine during pregnancy

OBJECTIVE

To evaluate glucose metabolism during pregnancy, we measured plasma fructosamine, glycated albumin, and the stable glycated hemoglobin of the light and dense erythrocytes.

STUDY DESIGN

The abnormal glucose tolerance group comprised patients with gestational diabetes and those with one abnormal value on a 75 gm oral glucose tolerance test. Erythrocyte fractionation was performed by capillary centrifugation.

RESULTS

In normal pregnancy glycated hemoglobin of the light erythrocytes was reduced in the second and third trimesters (3.42% +/- 0.62% [mean +/- SD] [n = 306] in the first trimester, 2.15% +/- 0.48% [n = 353] in the second, and 2.06% +/- 0.58% [n = 300] in the third), and dense erythrocytes were higher in the third trimester (first 4.59% +/- 0.46%, second 4.70% +/- 0.49%, third 5.29% +/- 0.73%). Glycated albumin and fructosamine followed a pattern similar to the light erythrocytes. The group with abnormal glucose tolerance had significantly higher levels of glycated hemoglobin of the light erythrocytes in the first and third trimesters and glycated hemoglobin of the dense erythrocytes and glycated albumin in all trimesters.

CONCLUSION

The biphasic change in nonfractionated glycated hemoglobin is the sum of the lower glycated hemoglobin of the light erythrocytes and the higher glycated hemoglobin of the dense erythrocytes in late pregnancy. The stable glycated hemoglobin of fractionated erythrocytes and the glycated albumin accurately reflect maternal glucose metabolism during pregnancy.

Fetal polycythemia and thrombocytopenia in pregnancies complicated by maternal diabetes mellitus

In 40 pregnancies complicated by maternal diabetes mellitus umbilical venous blood was obtained by cordocentesis within 24 hours of elective delivery at 36 to 40 weeks' gestation. The mean fetal hematocrit was significantly higher and the mean platelet count significantly lower than the corresponding values of our reference ranges. Furthermore, blood gas analysis demonstrated these fetuses to be normoxemic but acidemic. The degree of fetal acidemia was significantly associated with both maternal and fetal blood glucose concentrations. The fetal hematologic indices were significantly related to the maternal glycosylated hemoglobin percentage but not to the degree of fetal acidemia or to the maternal or fetal blood glucose concentration at the time of cordocentesis. Fetal acidemia, polycythemia, and thrombocytopenia may contribute to the increased incidence of late unexplained intrauterine deaths in pregnancies complicated by maternal diabetes mellitus.

Cord and maternal glycosylated haemoglobin levels: a study in Sudanese pregnant diabetic women

Blood glucose and glycosylated haemoglobin levels measured at delivery in 27 normal and 19 diabetic women were compared with those of the corresponding fetuses and their birthweights. In both groups, neonatal blood glucose levels were significantly higher (p much less than 0.001) than the maternal levels despite significantly lower (p much less than 0.001) glycosylated haemoglobin values in the neonates. In the control group, there was a significant correlation of maternal glycosylated haemoglobin with both cord glycosylated haemoglobin and birthweight ratio (p less than 0.01). The same was not obtained in the diabetic group, suggesting a dissociation in glucose homeostasis between the diabetic pregnant mother and her fetus.