Glynis P. Ross

A Randomized Controlled Trial Investigating the Effects of a Low-Glycemic Index Diet on Pregnancy Outcomes in Gestational Diabetes Mellitus

OBJECTIVE The prevalence of gestational diabetes mellitus (GDM) is rising. There is little evidence to demonstrate the effectiveness of one dietary therapy over another. We aimed to investigate the effect of a low–glycemic index (LGI) versus a conventional high-fiber diet on pregnancy outcomes, neonatal anthropometry, and maternal metabolic profile in GDM. RESEARCH DESIGN AND METHODS Ninety-nine women (age 26–42 years; mean ± SD prepregnancy BMI 24 ± 5 kg/m2) diagnosed with GDM at 20–32 weeks’ gestation were randomized to follow either an LGI (n = 50; target glycemic index [GI] ~50) or a high-fiber moderate-GI diet (HF) (n = 49; target GI ~60). Dietary intake was assessed by 3-day food records. Pregnancy outcomes were collected from medical records. RESULTS The LGI group achieved a modestly lower GI than the HF group (mean ± SEM 47 ± 1 vs. 53 ± 1; P < 0.001). At birth, there was no significant difference in birth weight (LGI 3.3 ± 0.1 kg vs. HF 3.3 ± 0.1 kg; P = 0.619), birth weight centile (LGI 52.5 ± 4.3 vs. HF 52.2 ± 4.0; P = 0.969), prevalence of macrosomia (LGI 2.1% vs. HF 6.7%; P = 0.157), insulin treatment (LGI 53% vs. HF 65%; P = 0.251), or adverse pregnancy outcomes. CONCLUSIONS In intensively monitored women with GDM, an LGI diet and a conventional HF diet produce similar pregnancy outcomes.

Why Does Ethnicity Affect Prevalence of Gestational Diabetes? The Underwater Volcano Theory

To study why gestational diabetes (GDM) is more common in some ethnic groups than others, we tested the hypothesis that GDM is more common in people who are temporally closer to developing non‐insulin‐dependent (Type 2) diabetes mellitus (NIDDM). The prevalence of GDM and the mean age of affected women in each major ethnic group were determined. From our database of NIDDM 6052 patients, the mean age of onset in each ethnic group was calculated and the mean difference between age of developing GDM and age of developing NIDDM derived (NIDDM–GDM age gap). This age gap was used to adjust for the susceptibility to GDM of each group. The overall prevalence of GDM was 6.7 % (CI 6.0 %–7.4 %). In Anglo‐Celtic women it was 3.0 % (CI 2.3 %–3.7 %). For the other ethnic groups the prevalence and odds ratio (OR) were: Chinese (15.0 % CI 11.8 %–18.2 % OR 5.6), Vietnamese (9.6 % CI 6.6 %–12.5 % OR 3.6), Indian (16.7 % CI 9.8 %–23.5 % OR 6.4), Arabic (7.3 % CI 4.6 %–10.1 % OR 2.5) and Aborigines (10.1 % CI 3.8 %–16.4 % OR 3.7). The OR for susceptibility to GDM did not change after adjustment for BMI and maternal age and it correlated significantly with the NIDDM–GDM age gap (r = −0.85; p = 0.03). However, it fell substantially after adjustment for NIDDM‐GDM age gap. For women of different ethnic origins there is a difference in the time gap between their pregnancies and the time at which they would on average be expected to develop diabetes. This difference may be an important factor underlying the higher prevalence of GDM in some ethnic populations.

Glycemic index and pregnancy: a systematic literature review.

Background/Aim. Dietary glycemic index (GI) has received considerable research interest over the past 25 years although its application to pregnancy outcomes is more recent. This paper critically evaluates the current evidence regarding the effect of dietary GI on maternal and fetal nutrition. Methods. A systematic literature search using MEDLINE, EMBASE, CINAHL, Cochrane Library, SCOPUS, and ISI Web of Science, from 1980 through September 2010, was conducted. Results. Eight studies were included in the systematic review. Two interventional studies suggest that a low-GI diet can reduce the risk of large-for-gestational-age (LGA) infants in healthy pregnancies, but one epidemiological study reported an increase in small-for-gestational-age (SGA) infants. Evidence in pregnancies complicated by gestational diabetes mellitus (GDM), though limited (n = 3), consistently supports the advantages of a low-GI diet. Conclusion. There is insufficient evidence to recommend a low-GI diet during normal pregnancy. In pregnancy complicated by GDM, a low-GI diet may reduce the need for insulin without adverse effects on pregnancy outcomes. Until larger-scale intervention trials are completed, a low-GI diet should not replace the current recommended pregnancy diets from government and health agencies. Further research regarding the optimal time to start a low-GI diet for maximum protection against adverse pregnancy outcomes is warranted.

Recommended changes to diagnostic criteria for gestational diabetes: Impact on workload

Background:  Gestational diabetes mellitus (GDM) is recognised as a significant problem in pregnancy. Changes to GDM diagnostic criteria have been proposed following analysis of data from the Hyperglycemia and Adverse Pregnancy Outcome (HAPO) study. We sought to assess the impact on the workload for GDM management in Australia that would occur if these changes were adopted.

Gestational Diabetes Mellitus in Early Pregnancy: Evidence for Poor Pregnancy Outcomes Despite Treatment.

OBJECTIVE Recent guidelines recommend testing at <24 weeks of gestation for maternal dysglycemia in “high-risk” women. Evidence to support the early identification and treatment of gestational diabetes mellitus (GDM) is, however, limited. We examined the prevalence, clinical characteristics, and pregnancy outcomes of high-risk women with GDM diagnosed at <24 weeks of gestation (early GDM) and those with pre-existing diabetes compared with GDM diagnosed at ≥24 weeks of gestation, in a large treated multiethnic cohort. RESEARCH DESIGN AND METHODS Outcomes from 4,873 women attending a university hospital antenatal diabetes clinic between 1991 and 2011 were examined. All were treated to standardized glycemic targets. Women were stratified as pre-existing diabetes (n = 65) or GDM diagnosed at <12 weeks of gestation (n = 68), at 12–23 weeks of gestation (n = 1,247), or at ≥24 weeks of gestation (n = 3,493). RESULTS Hypertensive disorders in pregnancy including pre-eclampsia, preterm delivery, cesarean section, and neonatal jaundice (all P < 0.001) were more prevalent in women with pre-existing diabetes and early GDM. Macrosomia (21.8% vs. 20.3%, P = 0.8), large for gestational age (39.6% vs. 32.8%, P = 0.4), and neonatal intensive care admission (38.5% vs. 39.7%, P = 0.9) in women in whom GDM was diagnosed at <12 weeks of gestation were comparable to rates seen in women with pre-existing diabetes. CONCLUSIONS Despite early testing and current best practice treatment, early GDM in high-risk women remains associated with poorer pregnancy outcomes. Outcomes for those in whom GDM was diagnosed at <12 weeks of gestation approximated those seen in pre-existing diabetes. These findings indicate the need for further studies to establish the efficacy of alternative management approaches to improve outcomes in these high-risk pregnancies.

Type 2 diabetes in pregnancy: a wolf in sheep's clothing.

Type 2 diabetes is now the most common form of pregestational diabetes. Recent data suggest that pregnancies complicated by type 2 diabetes are associated with unacceptably high fetal mortality and morbidity, at an incidence comparable to pregnancies complicated by type 1 diabetes. This review examines the literature on type 2 diabetes in pregnancy, including its incidence and potential complications. There is a need to highlight the dangers of type 2 diabetes in pregnancy to both patients and medical practitioners. Peri‐conception care needs to improve to achieve better pregnancy outcomes.

Can Common Clinical Parameters Be Used to Identify Patients Who Will Need Insulin Treatment in Gestational Diabetes Mellitus

OBJECTIVE To identify patients with gestational diabetes mellitus (GDM) who will need antenatal insulin treatment (AIT) by using a risk-prediction tool based on maternal clinical and biochemical characteristics at diagnosis. RESEARCH DESIGN AND METHODS Data from 3,009 women attending the Royal Prince Alfred Hospital GDM Clinic, Australia, between 1995 and 2010 were studied. A risk engine was developed from significant factors identified for AIT using a logistic regression model. RESULTS A total of 51% of GDM patients required AIT. Ethnicity, gestation at diagnosis, HbA1c, fasting and 60-min glucose at oral glucose tolerance test, BMI, and diabetes family history were significant independent determinants of AIT. Notably, only 9% of the attributable risk for AIT can be explained by the clinical factors studied. A modeled risk-scoring system was therefore a poor predictor of AIT. CONCLUSIONS Baseline maternal characteristics including HbA1c alone cannot predict the need for AIT in GDM. Lifestyle, compliance, or as yet unmeasured influences play a greater role in determining AIT.

Randomized Controlled Trial Investigating the Effects of a Low–Glycemic Index Diet on Pregnancy Outcomes in Women at High Risk of Gestational Diabetes Mellitus: The GI Baby 3 Study

OBJECTIVE Dietary interventions can improve pregnancy outcomes in women with gestational diabetes mellitus (GDM). We compared the effect of a low–glycemic index (GI) versus a conventional high-fiber (HF) diet on pregnancy outcomes, birth weight z score, and maternal metabolic profile in women at high risk of GDM. RESEARCH DESIGN AND METHODS One hundred thirty-nine women [mean (SD) age 34.7 (0.4) years and prepregnancy BMI 25.2 (0.5) kg/m2] were randomly assigned to a low-GI (LGI) diet (n = 72; target GI ∼50) or a high-fiber, moderate-GI (HF) diet (n = 67; target GI ∼60) at 14–20 weeks’ gestation. Diet was assessed by 3-day food records and infant body composition by air-displacement plethysmography, and pregnancy outcomes were assessed from medical records. RESULTS The LGI group achieved a lower GI than the HF group [mean (SD) 50 (5) vs. 58 (5); P < 0.001]. There were no differences in glycosylated hemoglobin, fructosamine, or lipids at 36 weeks or differences in birth weight [LGI 3.4 (0.4) kg vs. HF 3.4 (0.5) kg; P = 0.514], birth weight z score [LGI 0.31 (0.90) vs. HF 0.24 (1.07); P = 0.697], ponderal index [LGI 2.71 (0.22) vs. HF 2.69 (0.23) kg/m3; P = 0.672], birth weight centile [LGI 46.2 (25.4) vs. HF 41.8 (25.6); P = 0.330], % fat mass [LGI 10 (4) vs. HF 10 (4); P = 0.789], or incidence of GDM. CONCLUSIONS In intensively monitored women at risk for GDM, a low-GI diet and a healthy diet produce similar pregnancy outcomes.

The clinical significance of overt diabetes in pregnancy

To explore clinical implications of overt diabetes in pregnancy on antenatal characteristics, adverse neonatal outcome and diabetes risk post‐partum.

Antenatal Diagnosis of Fetal Genotype Determines if Maternal Hyperglycemia Due to a Glucokinase Mutation Requires Treatment

OBJECTIVE In women with hyperglycemia due to heterozygous glucokinase (GCK) mutations, the fetal genotype determines its growth. If the fetus inherits the mutation, birth weight is normal when maternal hyperglycemia is not treated, whereas intensive treatment may adversely reduce fetal growth. However, fetal genotype is not usually known antenatally, making treatment decisions difficult. HISTORY AND EXAMINATION We report two women with gestational diabetes mellitus resulting from GCK mutations with hyperglycemia sufficient to merit treatment. INVESTIGATION In both women, DNA from chorionic villus sampling, performed after high-risk aneuploidy screening, showed the fetus had inherited the GCK mutation. Therefore, maternal hyperglycemia was not treated. Both offspring had a normal birth weight and no peripartum complications. CONCLUSIONS In pregnancies where the mother has hyperglycemia due to a GCK mutation, knowing the fetal GCK genotype guides the management of maternal hyperglycemia. Fetal genotyping should be performed when fetal DNA is available from invasive prenatal diagnostic testing.