Carbohydrate and lipid metabolism in pregnancy: normal compared with gestational diabetes mellitus

Differential Expression of Glucose Transporters in Rabbit Placenta: Effect of Hypercholesterolemia in Dams1

Low birth weight is observed in rabbit offspring when maternal hypercholesterolemia is induced during gestation, but the related etiology is still unknown. Glucose is one of the most important substances during fetal development, and defect in glucose supply to fetus was related to pathophysiological mechanisms in intrauterine growth restriction. Thus, the aim of this work was to evaluate the impact of maternal hypercholesterolemia during rabbit gestation on the glucose metabolism and the routing of glucose transporters (SLC2 and SLC5 [previously known as GLUT and SGLT]) in placenta. In this study, maternal and offspring serum levels of glucose and insulin were evaluated for control and hypercholesterolemic groups, and the mRNA and protein expressions of placental SLCs were quantified by real-time RT-PCR and Western immunoblot, respectively. Our data demonstrate that maternal hypercholesterolemia during gestation: 1) induces offspring hypoglycemia; 2) does not modify the genetic and protein expressions of SLC2A1 and SLC2A4 (previously GLUT1 and GLUT4) in total placental extract; 3) downregulates the placental SLC5A1 (previously SGLT1) protein expression without affecting its mRNA levels; 4) impairs the translocation of SLC2A1 but not SLC2A4 from cytoplasmatic pool to the cell membrane surface. Then we assume that reduction of offspring birth weight in presence of maternal hypercholesterolemia may be related to the offspring's hypoglycemia and the reduction of the cell surface expression of placental SLC2A1.

Maternal and foetal resistin and adiponectin concentrations in normal and complicated pregnancies

OBJECTIVE

The aim of this study was to evaluate how resistin and adiponectin (ApN) are involved in maternal energy metabolism and foetal growth.

DESIGN

A cross-sectional study.

PATIENTS AND MEASUREMENTS

Resistin and ApN were measured in 30 healthy nonpregnant women, 73 pregnant women [10-41 weeks of gestation; 18 with gestational diabetes mellitus (GDM), five with pregnancy-induce hypertension (PIH), nine with pre-eclampsia (PE), eight with chronic hypertension (CH) and 33 normal] and 40 foetal samples (20-41 weeks of gestation; 18 from GDM mothers and 22 from normal mothers).

RESULTS

Resistin levels were significantly higher in normal pregnant women than in nonpregnant controls (13.7 +/- 2.1 vs. 6.3 +/- 1.6 ng/ml; P < 0.005) and showed a negative correlation with gestational age (P < 0.0001, r = -0.7). Only women with PE presented resistin levels significantly lower than normotensive women of the same gestational age (8.2 +/- 1.2 vs. 17.9 +/- 4.3 ng/ml; P < 0.005). ApN levels, although similar in normal pregnant women to those in nonpregnant controls, were significantly lower in women with GDM (37-41 weeks; 5.2 +/- 0.5 vs. 8.2 +/- 0.8 mg/l; P < 0.0001) and PE (20-37 weeks; 5.0 +/- 0.7 vs. 9.5 +/- 0.7 mg/l; P = 0.008) than those found in normal women matched for gestational age. Resistin was detected in the umbilical venous blood in foetuses from 20 to 41 weeks of gestation. In all newborns, both resistin and ApN levels were significantly higher than those recorded in adult life and did not correlate with maternal levels (P = ns, r = 0.03 for resistin and P = ns, r = -0.3 for ApN). Foetuses from diabetic mothers had ApN significantly lower than normal foetuses (26.8 +/- 2.6 vs. 37.5 +/- 3.5 mg/l; P = 0.02), while resistin levels were similar (17.3 +/- 3.7 vs. 18.2 +/- 1.5 ng/ml; P = ns).

CONCLUSION

The secretion pattern of ApN in normal and complicated pregnancies strongly suggests an involvement of ApN in insulin resistance during gestation, while resistin seems to have a minor role. Moreover, the detection of high levels of resistin and ApN in cord blood during gestation is consistent with a regulatory action of these adipokines on tissue differentiation and foetal growth.

Increased plasma acylation-stimulating protein correlates with hyperlipidemia at late gestation

OBJECTIVES

Obesity is often associated with negative consequences, including hyperlipidemia and insulin resistance. Weight gain during pregnancy is also associated with major lipid alterations. Fat storage is enhanced in early pregnancy. At late gestation, hyperlipidemia becomes a major manifestation. The acylation-stimulating protein (ASP) is a potent lipogenic adipocytokine that correlates with postprandial triglyceride (TG) clearance in vivo and has been linked to hyperlipidemic disorders. The role of ASP during a normal pregnancy is unknown. The objective of this study was to investigate plasma ASP levels in correlation with the lipid profile during late gestation.

RESEARCH METHODS AND PROCEDURES

Seventy healthy women at late gestation and 60 non-pregnant controls of similar age and prepregnancy BMI were included in a cross-sectional study. Fasting plasma ASP levels and the lipid profile of all of the women were measured.

RESULTS

ASP levels were markedly elevated in the pregnant women (66%, p < 0.001). ASP levels correlated strongly with the elevated levels of TGs (r = 0.608, p < 0.000), apolipoprotein B (0.519, p < 0.000), and low-density lipoprotein-cholesterol (r = 0.405, p < 0.000). Multivariate analysis adjusting for BMI and age showed that changes in ASP levels at late gestation were best predicted by TG and apoB levels, accounting for 53.8% of plasma ASP variation. For the controls, ASP strongly correlated with BMI, which was the only significant predictor of ASP levels.

DISCUSSION

Gestational hormone alterations during pregnancy may affect ASP function as a lipogenic factor. Increased plasma ASP levels at late gestation and their strong correlation with parameters reflecting very low-density lipoprotein accumulation are suggestive of ASP resistance, which may further contribute to the hyperlipidemic state, shifting energy in the form of TGs to the rapidly growing fetus.

Resistin: a hormone which induces insulin resistance is increased in normal pregnancy

AIMS

Resistin, a newly discovered adipokine, is thought to play a key role in the regulation of insulin resistance. The objectives of this study were to develop a nomogram of maternal plasma concentrations of resistin from 11 weeks of gestation to term and to determine whether resistin concentrations differ between normal and overweight pregnant women.

METHODS

In this cross-sectional study, plasma concentrations of resistin were determined in normal pregnant women of normal body mass index (BMI 18.5-24.9; n=261), overweight pregnant women (BMI > or =25; n=140), and non-pregnant women of normal BMI (n=40). Blood samples were collected once from each woman between the first trimester and term. Percentiles for resistin concentration were determined for five pre-specified windows of gestational age. Plasma resistin concentration was determined by immunoassay. Non-parametric statistics were used for analysis.

RESULTS

The median maternal plasma concentration of resistin between 11 to 14 weeks of gestation in women of normal weight was significantly higher than non-pregnant women; the plasma concentration of resistin increased with gestational age.

CONCLUSIONS

Normal pregnant women have a higher median plasma concentration of resistin than non-pregnant women and the concentration of this adipokine increases with advancing gestation. Alterations in the maternal plasma concentration of resistin during pregnancy could contribute to metabolic changes of pregnancy.

Blood ketone monitoring: a comparison between gestational diabetes and non-diabetic pregnant women

AIM

To measure ketonemia in a control population of pregnant women and in a population of women with gestational diabetes (GDM). To define a normal ketonemia threshold for the controls and to determine whether or not this value could play a role in the clinical management of women with GDM.

METHOD

Fifty-six women with a normal OGTT and 49 women with GDM were included and monitored from the 25th to the 37th week of pregnancy. Control subjects agreed to perform glycaemia and ketonemia self-monitoring 3 times a day. In addition, women with GDM were asked to measure their postprandial glycaemia. Glycaemia and ketonemia measurements were performed using Optium meters. Subjects kept a 24-hour food record twice a week.

RESULTS

The mean ketonemia was lower in the control group than in the GDM group (0.01+/-0.10 vs. 0.04+/-0.009 mmol/l; P<0.001). Ketonemia values measured before the midday meal and prior to the evening meal were lower for control subjects than for GDM patients (P=0.002 and P=0.005). Fasting ketonemia was unrelated to ketonuria in the GDM group, whereas there was a correlation in the control group (P=0.006). At least one chronic increase in ketonemia levels was observed in 47% of the women with GDM, compared with only 12% of controls. The lowest levels of evening glycaemia correlated with the highest levels of ketonemia; women with GDM reported lower food and carbohydrate intakes than controls (P<0.001).

CONCLUSION

This work has enabled the establishment of ketonemia reference standards in non-diabetic pregnant women. If ketonemia does indeed indicate overly restrictive dietary behavior, this parameter could be employed for monitoring adherence to the nutritional recommendations for GDM.

The validity of oral glucose tolerance test after 36 weeks’ gestation

OBJECTIVE

Secretion of anti-insulin hormones plateaus near term, questioning the validity of OGTT (oral glucose tolerance test) during that period. We aimed at assessing the feasibility of OGTT near term as compared to OGTT at 26-32 weeks.

PATIENTS AND METHODS

One thousand four hundred and eighty seven pregnant women were screened by GCT (glucose challenge test), and 282 (19%) of them performed an OGTT at 26th-32nd weeks ("early" OGTT) after meeting the threshold value for GCT. Forty-one women with abnormal and 16 with normal early OGTT underwent a repeated OGTT at 36-40 weeks' gestation ("late" OGTT). Blood glucose levels during GCT and OGTT were compared between women with early and late abnormal OGTT and women who converted from early abnormal to late normal OGTT.

RESULTS

Thirty-six out of 41 participants (88%) with early abnormal OGTT had abnormal test near term as well (Group I). Five women with an early abnormal OGTT converted to normal according to a late OGTT (Group II). These women had lower glucose levels on both late and early OGTT as compared with Group I. All 16 women who tested normal on early OGTT had a consistently normal late OGTT. Glucose levels for all 57 women did not significantly differ between early and late OGTT. The sensitivity, specificity, and positive and negative predictive values of late OGTT were 88%, 100%, 100%, and 76%, respectively.

CONCLUSION

The positive predictive value of late OGTT performed at 36-40 weeks' gestation is 100%. This test may be used to detect gestational diabetes in women near term.

Maternal obesity, metabolism, and pregnancy outcomes

About one third of all pregnant women in the United States are obese. Maternal obesity at conception alters gestational metabolic adjustments and affects placental, embryonic, and fetal growth and development. Neural tube defects and other developmental anomalies are more common in infants born to obese women; these defects have been linked to poor glycemic control. Preeclampsia, a gestational disorder occurring more frequently in obese women, appears to be due to a subclinical inflammatory state that impairs early placentation and development of its blood supply. Fetal growth and development during the last half of pregnancy depends on maternal metabolic adjustments dictated by placental hormones and the subsequent oxygen and nutrient supply. Maternal obesity affects these metabolic adjustments as well. Basal metabolic rates are significantly higher in obese women, and maternal fat gain is lower, possibly in response to altered leptin function. The usual increase in insulin resistance seen in late pregnancy is enhanced in obese mothers, causing marked postprandial increases in glucose, lipids, and amino acids and excessive fetal exposure to fuel sources, which in turn increases fetal size, fat stores, and risk for disease postnatally. Impaired glucose tolerance, gestational diabetes, and hyperlipidemia are more common among obese mothers. To date, little attention has been given to the role of diet among obese women in preventing these problems. However, studies of women with impaired glucose tolerance show that replacing refined carbohydrates and saturated fat with complex, low-glycemic carbohydrates and polyunsaturated fatty acids improves metabolic homeostasis and pregnancy outcomes. Thus, current dietary guidelines regarding the amount and type of carbohydrates and fat for nonpregnant women seem appropriate for pregnant women as well.

Hepatic and muscle insulin action during late pregnancy in the dog

We evaluated the effects of physiologic increases in insulin on hepatic and peripheral glucose metabolism in nonpregnant (NP) and pregnant (P; 3rd trimester) conscious dogs (n = 9 each) using tracer and arteriovenous difference techniques during a hyperinsulinemic euglycemic clamp. Insulin was initially (-150 to 0 min) infused intraportally at a basal rate. During 0-120 min (Low Insulin), the rate was increased by 0.2 mU x kg(-1) x min(-1), and from 120 to 240 min (High Insulin) insulin was infused at 1.5 mU x kg(-1) x min(-1). Insulin concentrations were significantly higher in NP than P during all periods. Matched subsets (n = 5 NP and 6 P) were identified. In the subsets, insulin was 7 +/- 1, 9 +/- 1, and 28 +/- 3 microU/ml (basal, Low Insulin, and High Insulin, respectively) in NP, and 5 +/- 1, 7 +/- 1, and 27 +/- 3 microU/ml in P. Net hepatic glucose output was suppressed similarly in both subsets (> or =50% with Low Insulin, 100% with High Insulin), as was endogenous glucose rate of appearance. During High Insulin, NP dogs required more glucose (10.8 +/- 1.5 vs. 6.2 +/- 1.0 mg x kg(-1) x min(-1), P < 0.05), and hindlimb (primarily skeletal muscle) glucose uptake tended to be greater in NP than P (18.6 +/- 2.5 mg/min vs. 13.6 +/- 2.0 mg/min, P = 0.06). The normal canine liver remains insulin sensitive during late pregnancy. Differing insulin concentrations in pregnant and nonpregnant women and excessive insulin infusion rates may explain previous findings of hepatic insulin resistance in healthy pregnant women.

Maternal insulin-like growth factors-I and -II act via different pathways to promote fetal growth

The placenta transports substrates and wastes between the maternal and fetal circulations. In mice, placental IGF-II is essential for normal placental development and function but, in other mammalian species, maternal circulating IGF-II is substantial and may contribute. Maternal circulating IGFs increase in early pregnancy, and early treatment of guinea pigs with either IGF-I or IGF-II increases placental and fetal weights by mid-gestation. We now show that these effects persist to enhance placental development and fetal growth and survival near term. Pregnant guinea pigs were infused with IGF-I, IGF-II (both 1 mg/kg.d), or vehicle sc from d 20-38 of pregnancy and killed on d 62 (term = 69 d). IGF-II, but not IGF-I, increased the mid-sagittal area and volume of placenta devoted to exchange by approximately 30%, the total volume of trophoblast and maternal blood spaces within the placental exchange region (+29% and +46%, respectively), and the total surface area of placenta for exchange by 39%. Both IGFs reduced resorptions, and IGF-II increased the number of viable fetuses by 26%. Both IGFs increased fetal weight by 11-17% and fetal circulating amino acid concentrations. IGF-I, but not IGF-II, reduced maternal adipose depot weights by approximately 30%. In conclusion, increased maternal IGF-II abundance in early pregnancy promotes fetal growth and viability near term by increasing placental structural and functional capacity, whereas IGF-I appears to divert nutrients from the mother to the conceptus. This suggests major and complementary roles in placental and fetal growth for increased circulating IGFs in early to mid-pregnancy.

Postpartum mood disorders may be related to a decreased insulin level after delivery

Postpartum mood disorders are very frequent complications of delivery. The prevalence of postpartum blue syndrome is around 25% and that of postpartum depression is around 10%. These disorders greatly affect the well-being of these newly delivering mothers. Currently, the etiology of postpartum mood disorders is still unknown. Although many hormones have been investigated for their possible roles in postpartum mood disorders, the results are still inconclusive. Several studies have shown that insulin increases gradually during pregnancy. The level of insulin secretion may double by the third trimester. Insulin level reaches a maximum before delivery and returns to the level before pregnancy after delivery. The drop in the insulin level during the postpartum period appears to be more sudden and abrupt than the rise of insulin level during pregnancy. Recent studies have showed that insulin affects the secretion of serotonin in the brain. While serotonergic nervous system is well known for its important role in the development of mood disorders, decreased insulin level may induce mood disorders through the mechanism of affecting serotonin secretion in the brain. In the current paper, we propose that the rapid decrease in insulin level during the postpartum period may be one of the causes of postpartum mood disorders. If the hypothesis is valid, clinicians may be able to prevent postpartum mood disorders by carbohydrate-rich food during the postpartum period to stimulate the secretion of insulin. A carbohydrate-rich diet may also become an adjunctive therapy in the treatment of postpartum mood disorders according to the present hypothesis.

Regulation of maternal metabolism by pituitary and placental hormones: roles in fetal development and metabolic programming

This review outlines the regulation of maternal metabolism by hormones, cytokines and growth factors, highlighting recent studies that implicate disordered somatolactogen signalling in the pathogenesis of perinatal growth failure and the development of the metabolic syndrome.

Aspects of placental growth hormone physiology

Placental growth hormone (PGH) has been known for 20 years. Nevertheless, its physiology is far from understood. In this review, basal aspects of PGH physiology are summarised and put in relation to the highly homologous pituitary growth hormone (GH). During normal pregnancy, PGH progressively replaces GH and reach maximum serum concentrations in the third trimester. A close relationship to insulin-like growth factor (IGF)-I and -II levels is observed. Furthermore, PGH levels are positively associated to fetal growth. The potential importance of growth hormone receptors and binding protein for PGH effects is discussed. Finally, the review outlines current knowledge of PGH in pathological pregnancies.

Glucagon secretion and autonomic signaling during hypoglycemia in late pregnancy

We examined net pancreatic norepinephrine (NE) spillover, pancreatic polypeptide (PP) release, and the decrement in C-peptide to identify factors involved in the blunted counterregulatory glucagon response in pregnancy. Conscious pregnant [pregnant hypoglycemic (Ph); 3rd trimester; n = 8] and nonpregnant [nonpregnant hypoglycemic (NPh); n = 6] dogs were studied during insulin-induced (approximately 12-fold basal insulin concentrations) hypoglycemia (plasma glucose 3.1 mM). Additional dogs were studied during hyperinsulinemic euglycemia [nonpregnant euglycemic (NPe), n = 4; pregnant euglycemic (Pe), n = 5; plasma glucose 6 mM]. Arterial glucagon concentrations declined similarly in NPe and Pe. Areas under the curve (AUCs) of the changes in glucagon and epinephrine were seven- and threefold greater in NPh than Ph (P < 0.05 between groups for both). Glucagon secretion fell below basal in NPe, Pe, and Ph but rose significantly in NPh. C-peptide declined 0.25 +/- 0.06, 0.12 +/- 0.11, 0.28 +/- 0.05, and 0.13 +/- 0.02 ng/ml in NPe, Pe, NPh, and Ph, respectively (P < 0.05, NPh vs. Ph). AUCs of NE spillover were 516 +/- 274, 265 +/- 303, 506 +/- 94, and -63 +/- 79 ng, respectively (P < 0.05, NPh vs. Ph). The AUC of PP release was approximately threefold greater in NPh than Ph (P < 0.05) but not different between euglycemic groups. The current evidence strongly suggests that the blunting of glucagon secretion during insulin-induced hypoglycemia in pregnancy is related to generalized impairment of a number of different signals, including parasympathetic and sympathoadrenal stimuli and altered sensing of circulating and/or intraislet insulin.

Short communication: A longitudinal study of serum adiponectin during normal pregnancy

Adiponectin is secreted from adipose tissue. Serum adiponectin levels are inversely correlated with body mass index (BMI) and also insulin resistance, independent of the BMI. A role for adiponectin in the development of insulin resistance has been implied in pregnancy. However, no studies have been performed to describe the individual longitudinal course of adiponectin in normal pregnancies. Therefore, we measured serum adiponectin during and after normal pregnancy in 11 healthy women. Serum levels peaked in midpregnancy and the lowest levels were seen in late pregnancy. An inverse association with maternal BMI was observed.

Oral glucose tolerance testing at gestational weeks < or =16 could predict or exclude subsequent gestational diabetes mellitus during the current pregnancy in high risk group

BACKGROUND

An oral glucose tolerance test with a result that is negative but close to the diagnostic cut-off in early pregnancy was hypothesized to serve as a predictor of subsequent gestational diabetes in a high risk group. The aim of the study was to determine those cut-off values of OGTT at gestational weeks < or =16, which can predict or exclude subsequent onset of GDM in a high risk group.

METHODS

Pregnant women at high risk of gestational diabetes (n = 163) underwent a 2-h, 75-g oral glucose tolerance test at gestational weeks < or =16 were analyzed in this study. In the event of a negative result, subsequent oral glucose tolerance tests were performed at gestational weeks 24-28 and 32-34. The sensitivity, the specificity, the positive and negative predictive values and the Odds ratio of the best cut-off values of fasting and postload glucose levels were calculated.

RESULTS

The best cut-off values to exclude subsequent GDM for fasting and postload glucose were 5.0 and 6.2 mmol/l, respectively. In combination, the best cut-off values were 5.3 mmol/l for fasting and 6.8 mmol/l for postload glucose, with negative predictive values of 0.97 and 0.71 and sensitivities of 96.9 and 86.3 at gestational weeks 24-28 and 32-34, respectively. Combination of these cut-off values with obesity proved to be very predictive for gestational diabetes by gestational weeks 32-34, with an Odds ratio of 6.0 [95% confidence interval: 1.7-21.0].

CONCLUSIONS

With regard to the very high negative predictive value of the method, pregnant women with glucose levels of < or =5.3 mmol/l at fasting and of < or = 6.8 mmol/l at postload in gestational weeks < or =16 should undergo subsequent oral glucose tolerance testing merely at gestational weeks 32-34. Approximately a quarter (24.5%) of the pregnant women at risk of gestational diabetes satisfied these criteria.

Pregnancy increases urinary loss of carnitine and reduces plasma carnitine in Korean women

This study compared plasma and urinary carnitine concentrations in pregnant and non-pregnant Korean women. The subjects were fifty pregnant women and thirty non-pregnant women aged 24-28 years. During the first trimester, dietary carnitine intakes in the pregnant women were much lower than in non-pregnant women (70.00 (SD 29.22) micromol/d), but over the course of pregnancy carnitine intake increased from 44.64 (SD 24.84) micromol/d during the first trimester to 96.11 (SD 36.56) micromol/d during the third trimester. Pregnant women had a significantly lower plasma carnitine concentration than non-pregnant women. Plasma concentrations of non-esterified carnitine, acid-soluble acylcarnitine and total carnitine were significantly lower during the second and third trimesters than the first. Plasma acid-insoluble acylcarnitine levels, which tended to be higher in the non-pregnant women compared with the pregnant women, increased significantly as gestation proceeded. The urinary excretion of non-esterified carnitine, acid-soluble acylcarnitine and total carnitine was significantly higher in the pregnant women during the first and second trimesters than in non-pregnant women and decreased significantly as gestation proceeded. We found that there was a significant decrease in plasma carnitine level even though dietary carnitine intake increased as gestation proceeded. The low urinary excretion of carnitine in late pregnancy may be caused by an increased demand during pregnancy.

Effect of placental function on fatty acid requirements during pregnancy

The fetus has an absolute requirement for the n-3/n-6 fatty acids and docosahexaenoic acid (22:6 n-3; DHA) in particular is essential for the development of the brain and retina. Most of the fat deposition in the fetus occurs in the last 10 weeks of pregnancy. The likely rate of DHA utilisation during late pregnancy cannot be met from dietary sources alone in a significant proportion of mothers. De novo synthesis makes up some of the shortfall but the available evidence suggests that the maternal adipose tissue makes a significant contribution to placental transport to the fetus. The placenta plays a crucial role in mobilising the maternal adipose tissue and actively concentrating and channelling the important n-3/n-6 fatty acids to the fetus via multiple mechanisms including selective uptake by the syncytiotrophoblast, intracellular metabolic channelling, and selective export to the fetal circulation. These mechanisms protect the fetus against low long-chain polyunsaturated fatty acid (LCPUFA) intakes in the last trimester of pregnancy and have the effect of reducing the maternal dietary requirement for preformed DHA at this time. As a result of these adaptations, small changes in the composition of the habitual maternal diet before pregnancy are likely to be more effective in improving LCPUFA delivery to the fetus than large dietary changes in late pregnancy. There is little evidence that DHA intake/status in the second half of pregnancy affects visual and cognitive function in the offspring, but more studies are needed, particularly in children born to vegetarian and vegan and mothers who may have very low intakes of DHA.

Advice that includes food sources of unsaturated fat supports future risk management of gestational diabetes mellitus

Abstract Women with gestational diabetes mellitus (GDM) have a greater risk of developing type 2 diabetes mellitus (DM) and heart disease than pregnant women without GDM. Advice given during the GDM pregnancy provides an opportunity to develop protective dietary patterns for the long-term management of this risk. Dietary guidelines for the prevention and management of type 2 DM support the inclusion of unsaturated fats, but food advice needs to target this outcome. The aim of this study was to compare the dietary intakes of women with GDM given general low-fat advice (control group) to women with GDM given the same advice with additional targets for food sources of unsaturated fats (intervention group). After approximately 6 weeks, the intervention group reported more ideal dietary fatty acid intakes than the control group, with polyunsaturated:saturated fat ratios of 1:1 and 0.4:1, respectively ( P < .001), assessed using repeated measures analysis of variance. These results confirm the need to include food sources of unsaturated fats in advice strategies to assure optimal protective eating habits in this at-risk group.

Gestational diabetes and nutritional recommendations

The goals of medical nutrition therapy for gestational diabetes mellitus (GDM) are to meet the maternal and fetal nutritional needs, as well as to achieve and maintain optimal glycemic control. Nutrition requirements during pregnancy are similar for women with and without GDM. The American Diabetes Association and the American College of Obstetrics and Gynecology recommend nutrition therapy for GDM that emphasizes food choices to promote appropriate weight gain and normoglycemia without ketonuria, and moderate energy restriction for obese women. Current controversies in GDM nutrition therapy involve manipulation of dietary composition (amounts and types of carbohydrates and fats), gestational weight gain, and energy and carbohydrate restriction. Randomized controlled trials are needed to determine which dietary compositions and patterns promote normoglycemia as well as optimal maternal and infant outcomes. Until better evidence is available, nutrition therapy will remain a cornerstone of GDM management with potential benefits that cannot be fully realized in clinical practice.

Pregnancy impairs the counterregulatory response to insulin-induced hypoglycemia in the dog

The impact of pregnancy on the counterregulatory response to insulin-induced hypoglycemia was examined in six nonpregnant (NP) and six pregnant (P; 3rd trimester) conscious dogs by tracer and arteriovenous difference techniques. After basal sampling, insulin was infused intraportally at 30 pmol.kg(-1).min(-1) for 180 min. Insulin rose from 70 +/- 15 to 1,586 +/- 221 pmol/l and 27 +/- 4 to 1,247 +/- 61 pmol/l in the 3rd h in NP and P, respectively. Arterial glucose fell from 5.9 +/- 0.2 to 2.3 +/- 0.2 mmol/l in P. Glucose was infused in NP to equate the rate of fall of glucose and the steady-state concentrations in the groups (5.9 +/- 0.2 to 2.3 +/- 0.1 mmol/l in NP). Glucagon was 32 +/- 6, 69 +/- 11, and 48 +/- 10 ng/l (basal and 1st and 3rd h) in NP, but the response was attenuated in P (34 +/- 5, 46 +/- 6, 41 +/- 9 ng/l). Cortisol and epinephrine rose similarly in both groups, but norepinephrine rose more in NP (Delta3.01 +/- 0.46 and Delta1.31 +/- 0.13 nmol/l, P < 0.05). Net hepatic glucose output (NHGO; micromol.kg(-1).min(-1)) increased from 10.6 +/- 1.8 to 21.2 +/- 3.3 in NP (3rd h) but did not increase in P (15.1 +/- 1.5 to 15.3 +/- 2.8 micromol.kg(-1).min(-1), P < 0.05 between groups). The glycogenolytic contribution to NHGO in NP increased from 5.8 +/- 0.7 to 10.4 +/- 2.5 micromol.kg(-1).min(-1) by 90 min but steadily declined in P. The increase in glycerol levels and the gluconeogenic contribution to NHGO were 50% less in P than in NP, but ketogenesis did not differ. The glucagon and norepinephrine responses to insulin-induced hypoglycemia are blunted in late pregnancy in the dog, impacting on the magnitude of the metabolic responses to the fall in glucose.

Adiponectin is reduced in gestational diabetes mellitus in normal weight women

BACKGROUND

Adiponectin is an adipose tissue-derived protein counteracting insulin resistance and inflammation. We have compared women with gestational diabetes mellitus (GDM; n = 22) and normal pregnancies (controls; n = 29) to evaluate whether adiponectin represents a link between endocrine function of adipose tissue and the development of diabetes during pregnancy.

METHODS

The participants were categorized according to their prepregnancy body mass index (BMI) into two classes: BMI < 25 and BMI = 25. Plasma concentrations of adiponectin, leptin and insulin were measured by radioimmunoassay (RIA). Total cholesterol, high density lipoprotein (HDL) cholesterol and triacylglycerol were determined by routine enzymatic methods. Expression of adiponectin/glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was determined by real-time reverse transcription polymerase chain reaction (RT-PCR) in subcutaneous adipose tissues obtained by excision at cesarean delivery.

RESULTS

Among individuals with GDM and BMI < 25 kg/m2 (n = 8), plasma adiponectin concentration was lower than in the controls (n = 20), 8.1 +/- 1.2 microg/mL vs. 12.2 +/- 1.1 microg/mL; p = 0.04). The mean plasma leptin concentrations did not differ between the GDM and control groups. Plasma concentrations of insulin and C-peptide were significantly higher among GDM than control individuals independent of BMI. For all the women included in the study, we found that plasma adiponectin only correlated negatively with prepregnancy and third-trimester (sampling day) BMI (p = 0.03 vs. p = 0.01). In abdominal subcutaneous adipose tissue of pregnant women, adiponectin mRNA levels were lower in GDM than in control subjects (0.77 +/- 0.18 vs. 1.39 +/- 0.15; p = 0.05).

CONCLUSIONS

These results indicate that low plasma adiponectin concentration is associated with GDM. In addition, we found that adiponectin mRNA levels in adipose tissue biopsies from GDM subjects were reduced.

Metformin and gestational diabetes

Pregnancy increases requirements for insulin secretion, increasing insulin resistance and demands on pancreatic b cells, promoting development of gestational diabetes (GD), particularly in women with preexisting insulin resistance, commonly in women with polycystic ovary syndrome. Preliminary studies suggest that metformin may have the unique potential to prevent the development of GD. We postulate that interventions that reduce insulin resistance and lower requirements for endogenous insulin secretion can preserve b-cell function and prevent the development of type 2 diabetes mellitus.

Intermediate metabolism in normal pregnancy and in gestational diabetes

Complex though integrated hormonal and metabolic changes characterize pregnancy. In the face of progressive decline in insulin action, glucose homeostasis is maintained through a compensatory increase in insulin secretion. This switches energy production from carbohydrates to lipids, making glucose readily available to the fetus. This precise and entangled hormonal and metabolic condition can, however, be disrupted and diabetic hyperglycemia can develop (gestational diabetes). The increase in plasma glucose level is believed to confer significant risk of complications to both the mother and the fetus and the newborn. Moreover, exposition of fetal tissues to the diabetic maternal environment can translate into an increased risk for development of diabetes and/or the metabolic syndrome in the adult life. In women with previous gestational diabetes, the risk of developing type 2 diabetes is greatly enhanced, to the point that GDM represents an early stage in the natural history of type 2 diabetes. In these women, accurate follow-up and prevention strategies are needed to reduce the subsequent development of overt diabetes. This paper will review current knowledge on the modifications occurring in normal pregnancy, while outlining the mechanisms. In this paper, we will review the changes of intermediary metabolism occurring during pregnancy. In particular, we will outline the mechanisms responsible for gestational diabetes; the link between these alterations and associated maternal and neonatal morbidity will be examined.

Atividade física e gestação: saúde da gestante não atleta e crescimento fetal

São reconhecidos os benefícios da prática de atividade física sobre o ciclo vital, sem consenso quanto à gestação. Este artigo reviu considerações e efeitos da prática da atividade física durante a gestação sobre a saúde da gestante não-atleta e o feto. Foram utilizados os bancos de dados Medline e Pubmed referentes ao período 1992-2002. Dentre os benefícios, os artigos destacam: prevenção e redução de lombalgias, de dores das mãos e pés e estresse cardiovascular, fortalecimento da musculatura pélvica, redução de partos prematuros e cesáreas, maior flexibilidade e tolerância à dor, controle do ganho ponderal e elevação da auto-estima da gestante. No feto, observou-se aumento do peso ao nascer e melhoria da condição nutricional. Não se encontraram recomendações de necessidades nutricionais para a gestante não-atleta. Não existiu consenso quanto às necessidades nutricionais e o tipo de atividade física dessa gestante, sendo o exercício na água o mais indicado. Porém destacaram-se diversas contra-indicações da prática de exercícios na gestação. Concluiu-se que a atividade física, sendo regular, moderada e controlada desde o início da gestação, promove benefícios para a saúde materna e fetal.

Progesterone in gestational diabetes mellitus: guilty or not guilty?

Insulin resistance is one of the metabolic changes in pregnancy, but only a fraction of women develop overt impaired glucose tolerance or frank diabetes. Most women are able to compensate this altered metabolic state by increasing the amount of insulin produced by the pancreatic beta cells. Progesterone might well be the key to the development of gestational diabetes. Previously high progesterone levels have already been shown to be correlated with the development of glucose abnormalities in pregnancy and now, in a new paper, progesterone receptor-knockout mice are found to have improved glucose tolerance. These mice showed increased insulin secretion, which is probably linked to the presence of increased numbers of beta cells in their pancreas. Is progesterone therefore the 'ultimate bad guy', prohibiting normal adaptation of the pancreatic beta-cell reserve during pregnancy?

Progesterone receptor knockout mice have an improved glucose homeostasis secondary to beta -cell proliferation

Gestational diabetes coincides with elevated circulating progesterone levels. We show that progesterone accelerates the progression of diabetes in female dbdb mice. In contrast, RU486, an antagonist of the progesterone receptor (PR), reduces blood glucose levels in both female WT and dbdb mice. Furthermore, female, but not male, PR-- mice had lower fasting glycemia than PR++ mice and showed higher insulin levels on glucose injection. Pancreatic islets from female PR-- mice were larger and secreted more insulin consequent to an increase in beta-cell mass due to an increase in beta-cell proliferation. These findings demonstrate an important role of progesterone signaling in insulin release and pancreatic function and suggest that it affects the susceptibility to diabetes.

Lipid metabolism in pregnancy and its consequences in the fetus and newborn

During early pregnancy there is an increase in body fat accumulation, associated with both hyperphagia and increased lipogenesis. During late pregnancy there is an accelerated breakdown of fat depots, which plays a key role in fetal development. Besides using placental transferred fatty acids, the fetus benefits from two other products: glycerol and ketone bodies. Although glycerol crosses the placenta in small proportions, it is a preferential substrate for maternal gluconeogenesis, and maternal glucose is quantitatively the main substrate crossing the placenta. Enhanced ketogenesis under fasting conditions and the easy transfer of ketones to the fetus allow maternal ketone bodies to reach the fetus, where they can be used as fuels for oxidative metabolism as well as lipogenic substrates. Although maternal cholesterol is an important source of cholesterol for the fetus during early gestation, its importance becomes minimal during late pregnancy, owing to the high capacity of fetal tissues to synthesize cholesterol. Maternal hypertriglyceridemia is a characteristic feature during pregnancy and corresponds to an accumulation of triglycerides not only in very low-density lipoprotein but also in low- and high-density lipoprotein. Although triglycerides do not cross the placental barrier, the presence of lipoprotein receptors in the placenta, together with lipoprotein lipase, phospholipase A2, and intracellular lipase activities, allows the release to the fetus of polyunsaturated fatty acids transported as triglycerides in maternal plasma lipoproteins. Normal fetal development needs the availability of both essential fatty acids and long chain polyunsaturated fatty acids, and the nutritional status of the mother during gestation has been related to fetal growth. However, excessive intake of certain long chain fatty acids may cause both declines in arachidonic acid and enhanced lipid peroxidation, reducing antioxidant capacity.

Metformin therapy throughout pregnancy reduces the development of gestational diabetes in women with polycystic ovary syndrome

OBJECTIVE

To assess whether metformin safely reduced development of gestational diabetes in women with the polycystic ovary syndrome (PCOS).

DESIGN

Prospective and retrospective study.

SETTING

Outpatient clinical research center.

PATIENT(S)

The prospective study included 33 nondiabetic women with PCOS who conceived while taking metformin and had live births; of these, 28 were taking metformin through delivery. The retrospective study included 39 nondiabetic women with PCOS who had live birth pregnancies without metformin therapy.

INTERVENTION(S)

Metformin, 2.55 g/d, throughout pregnancy in women with PCOS.

MAIN OUTCOME MEASURE(S)

Development of gestational diabetes in women with PCOS.

RESULT(S)

Before metformin therapy, after covariance adjustment for age, the two cohorts did not differ in height, weight, basal metabolic index, insulin, insulin resistance, or insulin secretion. Both cohorts had high fasting insulin, were insulin resistant, and had high insulin secretion. Among the 33 women who received metformin, gestational diabetes developed in 1 of 33 (3%) pregnancies versus 8 of 12 (67%) of their previous pregnancies without metformin. Among the 39 women who did not take metformin, gestational diabetes developed in 14 of 60 (23%) pregnancies. When all live births were combined, gestational diabetes occurred in 22 of 72 pregnancies (31%) in women who did not take metformin versus 1 of 33 pregnancies (3%) in those who took metformin. With gestational diabetes as the response variable and age at delivery and treatment group (metformin or no metformin) as explanatory variables, the odds ratio for gestational diabetes in women with metformin versus without metformin was 0.093 (95% CI: 0.011 to 0.795). With gestational diabetes in 93 pregnancies as the response variable and age at delivery and treatment group (metformin no metformin) as explanatory variables, the odds ratio of gestational diabetes in pregnancies in women taking metformin versus without metformin was 0.115 (95% CI: 0.014 to 0.938).

CONCLUSION(S)

In PCOS, use of metformin is associated with a 10-fold reduction in gestational diabetes (31% to 3%). It also reduces insulin resistance and insulin secretion, thus decreasing the secretory demands imposed on pancreatic beta-cells by insulin resistance and pregnancy.

Higher carbohydrate intake is associated with decreased incidence of newborn macrosomia in women with gestational diabetes

OBJECTIVE

To study the influence of energy and macronutrient intake on infant birthweight in women with gestational diabetes mellitus undergoing intensive management.

DESIGN

This prospective study evaluated the impact of intensive management of gestational diabetes on maternal and fetal morbidity, and addressed the relationship between food intake and infant birthweight.

SETTING

Fifteen maternity hospitals in northern France.

SUBJECTS

Ninety-nine women with gestational diabetes or gestational mild hyperglycemia diagnosed between 24 and 34 weeks of gestation were surveyed. After 1 was excluded because of a premature birth and 18 were excluded as underreporters, 80 women were included in the final analysis. Diet intake was assessed by a dietary history at the first interview, and by two 3-day diet records at the 3rd and 7th week after diagnosis.

RESULTS

In a forward-stepwise regression analysis (controlling for maternal age; smoking; parity; prepregnancy BMI; pregnancy weight gain; gestational duration; infant sex; fasting and 2-hour postprandial serum glucose; insulin therapy; and energy, fat, protein and carbohydrate intake during treatment) infant birthweight was positively associated with gestational duration (beta = +0.34, P<.002), and negatively with smoking (beta = -0.27, P<.02) and carbohydrate intake (beta = -0.24, P<.03). There were no large-for-gestational-age infants among women whose carbohydrate intake exceeded 210 g/day.

CONCLUSION

For women with gestational diabetes undergoing intensive management, higher carbohydrate intake is associated with decreased incidence of macrosomia.

APPLICATION

These findings suggest that nutrition counseling in gestational diabetes must be directed to maintain a sufficient carbohydrate intake (at least 250 g per day), which implies a low-fat diet to limit energy intake. A careful distribution of carbohydrate throughout the day and the use of low-glycemic index foods may help limit postprandial hyperglycemia.

Maternal and fetal serum lipid and lipoprotein concentrations and compositions in type 1 diabetic pregnancy: relationship with maternal glycemic control

The aim of this study was to determine maternal and fetal lipoprotein profiles in type 1 diabetic pregnancies differing in glycemic control. Serum lipid, apolipoprotein, and lipoprotein lipid concentrations were investigated in mothers with poorly controlled or well-controlled type 1 diabetes as reflected by hemoglobin A1c(HbA1c) concentrations performed by isolab column chromatography and in their macrosomic (body wt = 4650 +/- 90 g) or appropriate-for-gestational-age newborns (body wt = 3616 +/- 68 g), and these levels were compared with those in healthy mothers and in their control newborns (body wt = 3290 +/- 45 g). In mothers with well-controlled diabetes and in their infants, serum lipid, apolipoprotein, and lipoprotein lipid concentrations were comparable to those in control mothers and in their control newborns. Mothers with poorly controlled diabetes presented higher serum triglyceride and apoprotein B-100 (apo B-100) levels but lower apo A-I and HDL3 cholesterol and phospholipid levels as compared with control values. In their macrosomic newborns, all serum lipid, apolipoprotein, and lipoprotein lipid levels were higher than those in control newborns. Maternal HbA1c and triglyceride levels in late gestation were significant predictors of fetal lipids and lipoproteins in the poorly controlled diabetes group. In conclusion, when under good metabolic control, type 1 diabetes did not affect maternal and fetal lipid levels. However, when under poor metabolic control, type 1 diabetes is associated with maternal and fetal lipoprotein abnormalities.