Pregnancy-induced rise in serum C-peptide concentrations in women with type 1 diabetes

Pregnancy induces longitudinal changes in urinary C-peptide creatinine ratio in women with type 1 diabetes

AIMS

Changes in maternal serum C-peptide have been described during pregnancy in women with Type 1 diabetes. We aimed to determine whether in these women, C-peptide, as measured by the urinary C-peptide creatinine ratio (UCPCR), display changes during the course of pregnancy and in the postpartum period.

METHODS

In this longitudinal study including 26 women, UCPCR was measured in the first, second, and third trimester of pregnancy, and postpartum, using a high sensitivity two-step chemiluminescent microparticle immunoassay.

RESULTS

UCPCR was detectable in 7/26 (26.9%) participants in the first trimester, 10/26 (38.4%) in the second trimester, and 18/26 (69.2%) in the third trimester. Changes in UCPCR concentrations were observed throughout pregnancy, significantly increasing from first to third trimester. UCPCR concentration in the three trimesters was associated with a shorter duration of diabetes and in the third trimester also with first trimester UCPCR.

CONCLUSION

UCPCR detects longitudinal changes during pregnancy in women with type 1 diabetes mellitus, more marked in those with shorter diabetes duration.

Pregnancy induces pancreatic insulin secretion in women with long-standing type 1 diabetes

INTRODUCTION

Pregnancy entails both pancreatic adaptations with increasing β-cell mass and immunological alterations in healthy women. In this study, we have examined the effects of pregnancy on β-cell function and immunological processes in long-standing type 1 diabetes (L-T1D).

RESEARCH DESIGN AND METHODS

Fasting and stimulated C-peptide were measured after an oral glucose tolerance test in pregnant women with L-T1D (n=17) during the first trimester, third trimester, and 5-8 weeks post partum. Two 92-plex Olink panels were used to measure proteins in plasma. Non-pregnant women with L-T1D (n=30) were included for comparison.

RESULTS

Fasting C-peptide was detected to a higher degree in women with L-T1D during gestation and after parturition (first trimester: 64.7%, third trimester: 76.5%, and post partum: 64.7% vs 26.7% in non-pregnant women). Also, total insulin secretion and peak C-peptide increased during pregnancy. The plasma protein levels in pregnant women with L-T1D was dynamic, but few analytes were functionally related. Specifically, peripheral levels of prolactin (PRL), prokineticin (PROK)-1, and glucagon (GCG) were elevated during gestation whereas levels of proteins related to leukocyte migration (CCL11), T cell activation (CD28), and antigen presentation (such as CD83) were reduced.

CONCLUSIONS

In summary, we have found that some C-peptide secretion, that is, an indirect measurement of endogenous insulin production, is regained in women with L-T1D during pregnancy, which might be attributed to elevated peripheral levels of PRL, PROK-1, or GCG.

C-Peptide-Positive, Autoantibody-Negative Type 1 Diabetes Mellitus

A 30-year-old female previously diagnosed with C-peptide (CP)-positive, autoantibody-negative type 1 diabetes mellitus (T1DM) at 19 years old presented to the clinic at age 28 for management of diabetes mellitus (DM) that had previously been controlled by insulin since diagnosis. Laboratory results from May 2011 showed low-normal C-peptide of 1 ng/mL (normal range: 0.8-4 ng/mL) with no corresponding glucose, glutamic acid decarboxylase (GAD)-65 antibody (GADA) of <1 U/mL (N<1.1 U/mL at the time of laboratory draw), and HbA1c of 6.4%. Almost 10 years later, in December 2020, laboratory results showed normal C-peptide of 2.1 ng/mL with a glucose of 198 mg/dL, GAD-65 antibody of 38.2 U/mL (current reference range: 0-5 U/mL), negative pancreatic islet antibody (IA), and undetectable zinc transporter 8 (ZnT8) antibody, consistent with a diagnosis of T1DM.

This increase in CP indicates the possibility of pancreatic beta cell regeneration and/or increased function. The commonly accepted belief that individuals with T1DM quickly lose all function of pancreatic beta cells has led to academic consequences; many immunotherapy clinical trials’ inclusion criteria require participants to have a new diagnosis of T1DM based on the assumption that those with a longer duration of diabetes have unrecoverable cessation of insulin secretion. CP could influence inflammation, microvascular circulation, and endothelial function. Further, it could affect the neuronal and glomerular structure and/or function. These potential functions of CP are seen by the correlation between measurable CP levels and decreased diabetic complication rates.

Awakened Beta-Cell Function Decreases the Risk of Hypoglycemia in Pregnant Women with Type 1 Diabetes Mellitus

Diabetes in pregnancy creates many problems for both the mother and child. Pregnant women with type 1 diabetes experience more frequent hypoglycemic and hyperglycemic episodes. This study aimed to determine the risk of clinically significant biochemical hypoglycemia (CSBH) by HbA1c, fasting C-peptide, mean plasma glucose (PG), and insulin dose in pregnant women type 1 diabetes mellitus according to each trimester of the pregnancy. Methods. We conducted a prospective observational study of 84 pregnant women with type 1 diabetes in an academic hospital. To present the hypoglycemia, we divided the participants into two groups: those who did not have clinically significant biochemical hypoglycemia (CSBH−; n = 30) and those who had clinically significant biochemical hypoglycemia (CSBH+; n = 54). Results. In the first, second, and third trimesters, the duration of T1DM, fasting C-peptide, and mean glucose concentration was inversely associated with CSBH. Conclusions. Insulin overdose is the most common risk factor for hypoglycemia. In pregnant women with type 1 diabetes with elevated fasting C-peptide levels, the insulin dose should be diminished to reduce the risk of hypoglycemia.

N-3 PUFA and Pregnancy Preserve C-Peptide in Women with Type 1 Diabetes Mellitus

Type 1 diabetes (T1DM) is an autoimmune disease characterized by the gradual loss of β-cell function and insulin secretion. In pregnant women with T1DM, endogenous insulin production is absent or minimal, and exogenous insulin is required to control glycemia and prevent ketoacidosis. During pregnancy, there is a partial decrease in the activity of the immune system, and there is a suppression of autoimmune diseases. These changes in pregnant women with T1DM are reflected by Langerhans islet enlargement and improved function compared to pre-pregnancy conditions. N-3 polyunsaturated fatty acids (n-3 PUFA) have a protective effect, affect β-cell preservation, and increase endogenous insulin production. Increased endogenous insulin production results in reduced daily insulin doses, better metabolic control, and adverse effects of insulin therapy, primarily hypoglycemia. Hypoglycemia affects most pregnant women with T1DM and is several times more common than that outside of pregnancy. Strict glycemic control improves the outcome of pregnancy but increases the risk of hypoglycemia and causes maternal complications, including coma and convulsions. The suppression of the immune system during pregnancy increases the concentration of C-peptide in women with T1DM, and n-3 PUFA supplements serve as the additional support for a rise in C-peptide levels through its anti-inflammatory action.

Supplementation of EPA and DHA in pregnant women with type 1 diabetes mellitus

BACKGROUND/OBJECTIVE

Lower proportions of n-3 PUFAs have been observed in neonates born to diabetic mothers. We aimed to investigate the association between DHA and EPA supplementation during pregnancy complicated with type 1 diabetes on concentration and proportion of fatty acids in maternal and foetal blood.

SUBJECTS AND METHODS

We conducted a prospective randomized, single-blinded, placebo-controlled trial of 111 eligible pregnant women with type 1 diabetes and presented the results of 84 (intervention arm and control arm comprised 42 participants each) of them who successfully finished the trial in an academic hospital. The initiation of EPA and DHA supplementation or placebo started at randomization visit on gestational week 11-12. Blood samples were taken on the first (screening) visit to the clinic (1st trimester, between 8th and 10th gestational week, GW), then in the second trimester (19-24th GW) and third trimester (30th-33rd GW). On the delivery day, a blood sample was taken on fasting just before birth. The umbilical vein blood sample was taken shortly after the delivery.

RESULTS

We found a significant increase in the intervention group when compared the first and the third trimester for n-3 PUFAs concentration, 4.3 mg/L (3.3-7.6): 10.0 mg/L (7.1-13.7), p < .001. In the intervention group, the concentration of DHA in maternal vein serum was 11.4 mg/L (7.7-17.5), and in umbilical vein serum, it was 5.1 mg/L (3.0-7.7), which was significantly higher than that in the control group, maternal vein serum: median 9.2 mg/L(6.0-12.3), p = .03 and umbilical vein serum: median 3.4 mg/L (2.1-5.6), p = .009.

CONCLUSION

The increased weight gain in pregnancy and concentration and proportions of DHA, n-3 PUFAs with a decreased proportion of AA, n-6 PUFAs, and AA/DHA ratio in maternal and umbilical vein serum summarize the effect of supplementation with EPA and DHA.

Plasma Exosome-Enriched Extracellular Vesicles From Lactating Mothers With Type 1 Diabetes Contain Aberrant Levels of miRNAs During the Postpartum Period

Type 1 diabetes is an immune-driven disease, where the insulin-producing beta cells from the pancreatic islets of Langerhans becomes target of immune-mediated destruction. Several studies have highlighted the implication of circulating and exosomal microRNAs (miRNAs) in type 1 diabetes, underlining its biomarker value and novel therapeutic potential. Recently, we discovered that exosome-enriched extracellular vesicles carry altered levels of both known and novel miRNAs in breast milk from lactating mothers with type 1 diabetes. In this study, we aimed to characterize exosomal miRNAs in the circulation of lactating mothers with and without type 1 diabetes, hypothesizing that differences in type 1 diabetes risk in offspring from these groups are reflected in the circulating miRNA profile. We performed small RNA sequencing on exosome-enriched extracellular vesicles extracted from plasma of 52 lactating mothers around 5 weeks postpartum (26 with type 1 diabetes and 26 age-matched controls), and found a total of 2,289 miRNAs in vesicles from type 1 diabetes and control libraries. Of these, 176 were differentially expressed in plasma from mothers with type 1 diabetes (167 upregulated; 9 downregulated, using a cut-off of abs(log2FC) >1 and FDR adjusted p-value <0.05). Extracellular vesicles were verified by nanoparticle tracking analysis, transmission electron microscopy and immunoblotting. Five candidate miRNAs were selected based on their involvement in diabetes and immune modulation/beta-cell functions: hsa-miR-127-3p, hsa-miR-146a-5p, hsa-miR-26a-5p, hsa-miR-24-3p and hsa-miR-30d-5p. Real-time qPCR validation confirmed that hsa-miR-146a-5p, hsa-miR-26a-5p, hsa-miR-24-3p, and hsa-miR-30d-5p were significantly upregulated in lactating mothers with type 1 diabetes as compared to lactating healthy mothers. To determine possible target genes and affected pathways of the 5 miRNA candidates, computational network-based analyses were carried out with TargetScan, mirTarBase, QIAGEN Ingenuity Pathway Analysis and PantherDB database. The candidates showed significant association with inflammatory response and cytokine and chemokine mediated signaling pathways. With this study, we detect aberrant levels of miRNAs within plasma extracellular vesicles from lactating mothers with type 1 diabetes during the postpartum period, including miRNAs with associations to disease pathogenesis and inflammatory responses.

Reappearance of C-Peptide During the Third Trimester of Pregnancy in Type 1 Diabetes: Pancreatic Regeneration or Fetal Hyperinsulinism?

OBJECTIVE

We assessed longitudinal patterns of maternal C-peptide concentration to examine the hypothesis of β-cell regeneration in pregnancy with type 1 diabetes.

RESEARCH DESIGN AND METHODS

C-peptide was measured on maternal serum samples from 127 participants (12, 24, and 34 weeks) and cord blood during the Continuous Glucose Monitoring in Women With Type 1 Diabetes in Pregnancy Trial (CONCEPTT). C-peptide was measured using a highly sensitive direct and solid-phase competitive electrochemiluminescent immunoassay.

RESULTS

Three discrete patterns of maternal C-peptide trajectory were identified: pattern 1, undetectable throughout pregnancy, n = 74 (58%; maternal C-peptide <3 pmol/L); pattern 2, detectable at baseline, n = 22 (17%; maternal C-peptide 7-272 pmol/L at baseline); and pattern 3, undetectable maternal C-peptide at 12 and 24 weeks, which first became detectable at 34 weeks, n = 31 (24%; maternal C-peptide 4-26 pmol/L at 34 weeks). Baseline characteristics and third trimester glucose profiles of women with pattern 1 and pattern 3 C-peptide trajectories were similar, but women in pattern 3 had suboptimal glycemia (50% time above range) at 24 weeks' gestation. Offspring of women with pattern 3 C-peptide trajectories had elevated cord blood C-peptide (geometric mean 1,319 vs. 718 pmol/L; P = 0.007), increased rates of large for gestational age (90% vs. 60%; P = 0.002), neonatal hypoglycemia (42% vs. 14%; P = 0.001), and neonatal intensive care admission (45% vs. 23%; P = 0.023) compared with pattern 1 offspring.

CONCLUSIONS

First maternal C-peptide appearance at 34 weeks was associated with midtrimester hyperglycemia, elevated cord blood C-peptide, and high rates of neonatal complications. This suggests transfer of C-peptide from fetal to maternal serum and is inconsistent with pregnancy-related β-cell regeneration.

Ontology of the apelinergic system in mouse pancreas during pregnancy and relationship with β-cell mass

The apelin receptor (Aplnr) and its ligands, Apelin and Apela, contribute to metabolic control. The insulin resistance associated with pregnancy is accommodated by an expansion of pancreatic β-cell mass (BCM) and increased insulin secretion, involving the proliferation of insulin-expressing, glucose transporter 2-low (Ins+Glut2LO) progenitor cells. We examined changes in the apelinergic system during normal mouse pregnancy and in pregnancies complicated by glucose intolerance with reduced BCM. Expression of Aplnr, Apelin and Apela was quantified in Ins+Glut2LO cells isolated from mouse pancreata and found to be significantly higher than in mature β-cells by DNA microarray and qPCR. Apelin was localized to most β-cells by immunohistochemistry although Aplnr was predominantly associated with Ins+Glut2LO cells. Aplnr-staining cells increased three- to four-fold during pregnancy being maximal at gestational days (GD) 9-12 but were significantly reduced in glucose intolerant mice. Apelin-13 increased β-cell proliferation in isolated mouse islets and INS1E cells, but not glucose-stimulated insulin secretion. Glucose intolerant pregnant mice had significantly elevated serum Apelin levels at GD 9 associated with an increased presence of placental IL-6. Placental expression of the apelinergic axis remained unaltered, however. Results show that the apelinergic system is highly expressed in pancreatic β-cell progenitors and may contribute to β-cell proliferation in pregnancy.

Falling insulin requirement in late pregnancy: association with obstetric and neonatal outcomes

OBJECTIVE

To investigate whether diminishing insulin requirement in the third trimester is associated with placental dysfunction.

STUDY DESIGN

Two-year retrospective cohort study at one tertiary care center of women with pregestational or gestational diabetes, their insulin requirements, and complications associated with placental dysfunction.

RESULTS

Of 157 women, 21 (13%) experienced declining insulin requirement, with average decline of 28% at 34 weeks. They were more likely to have pregestational diabetes (71.4% vs. 42.6%; p < 0.01) and delivered earlier (median 36w4d vs. 37w4d; p < 0.01). There was no difference in placental dysfunction related complications (33% vs. 24%; p = 0.37). There was an increased rate of polyhydramnios (42.9% vs. 8.8%; p < 0.01). NICU admission (62% vs. 33%; p < 0.01) and neonatal respiratory distress (52% vs. 24%; p < 0.01) was higher in cases of declining insulin requirement independent of gestational age.

CONCLUSIONS

A decline in insulin requirement should raise concern for increased risk of NICU admission and neonatal respiratory distress.

Association of Cognitive Function and Retinal Neural and Vascular Structure in Type 1 Diabetes

CONTEXT

Cognitive dysfunction is a growing and understudied public health issue in the aging type 1 diabetic population and is difficult and time-consuming to diagnose. Studies in long duration type 1 diabetes have reported the presence of proliferative diabetic retinopathy was associated with cognitive dysfunction.

OBJECTIVE

This study assessed whether structural and vascular abnormalities of the retina, representing an extension of the central nervous system, are associated with cognitive impairment and other complications of type 1 diabetes.

METHODS

An observational cross-sectional study of individuals with 50 or more years of type 1 diabetes (Joslin Medalist Study) was conducted at a university hospital in the United States. The study included 129 participants with complete cognitive testing. Validated cognitive testing measures included psychomotor speed, and immediate, and delayed memory. Optical coherence tomography (OCT) and OCT angiography (OCTA) were performed to obtain neural retinal layer thicknesses and vascular density for superficial (SCP) and deep retinal capillary plexus (DCP). Multivariable modeling was adjusted for potential confounders associated with outcomes in unadjusted analyses.

RESULTS

Decreased vessel density of the SCP and DCP was associated with worse delayed memory (DCP: P = .002) and dominant hand psychomotor speed (SCP: P = .01). Thinning of the retinal outer nuclear layer was associated with worse psychomotor speed both in nondominant and dominant hands (P = .01 and P = .05, respectively). Outer plexiform layer thickness was associated with delayed memory (P = .04).

CONCLUSION

These findings suggest that noninvasive retinal imaging using OCT and OCTA may assist in estimating the risks for cognitive dysfunction in people with type 1 diabetes.

Decreasing Insulin Requirements in Pregnancy With Pre-existing or Gestational Diabetes: Management Practices Across Canada

Decreasing insulin requirements in pregnant women with preexisting or gestational diabetes has been attributed to placental insufficiency, which results in increased surveillance or early delivery. This practice is not evidence based. A 5-item questionnaire was administered electronically to a convenience sample of Canadian resident and staff obstetrician-gynaecologists and maternal-fetal medicine specialists. Practice patterns varied widely among the 142 survey respondents, and this variation did not correlate to their level of training. There is a paucity of evidence to guide the management of patients with decreasing insulin requirements, which is reflected in varied and possibly unnecessary clinical interventions.

A Review of the Pathophysiology and Management of Diabetes in Pregnancy

Diabetes is a common metabolic complication of pregnancy and affected women fall into two subgroups: women with pre-existing diabetes and those with gestational diabetes mellitus (GDM). When pregnancy is affected by diabetes, both mother and infant are at increased risk for multiple adverse outcomes. A multidisciplinary approach to care before, during, and after pregnancy is effective in reducing these risks. The PubMed database was searched for English language studies and guidelines relating to diabetes in pregnancy. The following search terms were used alone and in combination: diabetes, pregnancy, gestational diabetes, GDM, prepregnancy, and preconception. A date restriction was not applied. Results were reviewed by the authors and selected for inclusion based on relevance to the topic. Additional articles were identified by manually searching reference lists of included articles. Using data from this search we herein summarize the evidence relating to pathophysiology and management of diabetes in pregnancy. We discuss areas of controversy including the method and timing of diagnosis of GDM, and choice of pharmacologic agents to treat hyperglycemia during pregnancy. Therefore, this review is intended to serve as a practical guide for clinicians who are caring for women with diabetes and their infants.

Possible mechanisms involved in improved beta cell function in pregnant women with type 1 diabetes

Pregnancy is known to be associated with an increased demand for insulin that is normally compensated by an increased beta cell mass and insulin secretion. Recent studies have suggested enhanced beta cell function during pregnancy in women with type 1 diabetes (T1D). To explore the possible mechanisms behind enhanced beta cell function during pregnancy in women with T1D we investigated the impact of circulating factors in serum from nine women from each group of pregnant women with and without T1D, after pregnancy and non-diabetic non-pregnant women on rat islet cell proliferation and apoptosis, and on T-lymphocyte activation. In addition, circulating levels of pancreatic hormones and selected cytokines and adipokines were measured. Rat islet cell proliferation was higher in serum from pregnant women with T1D (p < 0.05) compared to T1D women after pregnancy. Apoptosis in INS-1E cell was lower (p < 0.05) in serum from pregnant women with T1D compared to T1D women after pregnancy. T-lymphocyte cell (Jurkat) proliferation was reduced by serum from pregnant women without T1D only (p < 0.05). Higher C-peptide levels and lower levels of ghrelin, IL-6, MCP-1, IL-8 and adipsin were observed in pregnant women with T1D compared to T1D women after pregnancy. In conclusion, the improved beta cell function in women with T1D during pregnancy may be due to lower levels of proinflammatory cytokines and/or higher levels of pregnancy-associated growth factors.

Pregnant type 1 diabetes women with rises in C-peptide display higher levels of regulatory T cells: A pilot study

AIM

During pregnancy of type 1 diabetes (T1D) women, a C peptide rise has been described, which mechanism is unclear. In T1D, a defect of regulatory T cells (Tregs) and its major controlling cytokine, interleukin-2 (IL2), is observed.

METHODS

Evolution of clinical, immunological (Treg (CD4+CD25hiCD127-/loFoxp3+ measured by flow cytometry and IL2 measured by luminex xMAP technology) and diabetes parameters (insulin dose per day, HbA1C, glycaemia, C peptide) was evaluated in 13 T1D women during the three trimesters of pregnancy and post-partum (PP, within 6 months) in a monocentric pilot study. Immunological parameters were compared with those of a healthy pregnant cohort (QuTe).

RESULTS

An improvement of beta cell function (C peptide rise and/or a decrease of insulin dose-adjusted A1c index that estimate individual exogenous insulin need) was observed in seven women (group 1) whereas the six others (group 2) did not display any positive response to pregnancy. A higher level of Tregs and IL2 was observed in group 1 compared to group 2 during pregnancy and at PP for Tregs level. However, compared to the healthy cohort, T1D women displayed a Treg deficiency CONCLUSION: This pilot study highlights that higher level of Tregs and IL2 seem to allow improvement of endogenous insulin secretion of T1D women during pregnancy.

Hypoglycaemia

In health hypoglycaemia is rare and occurs only in circumstances like extreme sports. Hypoglycaemia in type 1 Diabetes (T1D) and advanced type 2 Diabetes (T2D) are the result of interplay between absolute or relative insulin access and defective glucose counterregulation. The basic mechanism is, failure of decreasing insulin and failure of the compensatory increasing counterregulatory hormones at the background of falling blood glucose. Any person with Diabetes on anti-diabetic medication who behaves oddly in any way whatsoever is hypoglycaemic until proven otherwise. Hypoglycaemia can be a terrifying experience for a patient with Diabetes. By definition, hypoglycaemic symptoms are subjective and vary from person to person and even episode to episode in same person. Fear of iatrogenic hypoglycaemia is a major barrier in achieving optimum glycaemic control and quality of life which limits the reduction of diabetic complications. Diabetes patients with comorbidities especially with chronic renal failure, hepatic dysfunction, major limb amputation, terminal illness, cognitive dysfunction etc. are more vulnerable to hypoglycaemia. In most cases, prompt glucose intake reverts hypoglycaemia. Exogenous insulin in T1D and insulin treated advanced T2D have no control by pancreatic regulation. Moreover, failure of increase of glucagon and attenuated secretion in epinephrine causes the defective glucose counterregulation. In this comprehensive review, I will try to touch all related topics for better understanding of hypoglycaemia.

Augmented insulin secretory response in early pregnancy

AIMS/HYPOTHESIS

This study aimed to examine changes in the insulin secretory response in early pregnancy, while accounting for changes in insulin sensitivity.

METHODS

This is a secondary analysis of a previously conducted longitudinal physiological study. In 34 women, insulin secretory response (by IVGTT) and insulin sensitivity (by euglycaemic clamp) were assessed prior to pregnancy, in early pregnancy (12-14 weeks gestation) and in late pregnancy (34-36 weeks gestation). Using mixed-effects models, we compared insulin secretory response and sensitivity in early pregnancy to the same variables prior to pregnancy and in late pregnancy, with adjustment for age, obesity status and gestational diabetes mellitus (GDM). We examined changes in insulin secretory response after adjustment for insulin sensitivity using both multivariate modelling and the disposition index (DI). We explored the relationship between insulin secretory response and circulating hormones.

RESULTS

The insulin secretory response increased from prior to pregnancy to early pregnancy (unadjusted mean [SD] first-phase insulin response 465.1 [268.5] to 720 [358.2], p < 0.0001) and from early pregnancy to late pregnancy (to 924 [494.6], p = 0.01). Insulin sensitivity increased from prior to pregnancy to early pregnancy (insulin sensitivity index 0.10 [0.04] to 0.12 [0.05], p = 0.001) and decreased in late pregnancy (to 0.06 [0.03], p < 0.0001). Accounting for changes in insulin sensitivity, using either multivariate modelling or the DI, did not attenuate the early-pregnancy augmentation of insulin secretory response. Leptin was positively associated with insulin secretory response, independent of insulin sensitivity and adiposity (p = 0.004). Adjustment for leptin attenuated the observed augmentation of insulin secretory response in early pregnancy (adjusted mean change 121.5, p = 0.13).

CONCLUSIONS/INTERPRETATION

The insulin secretory response increases markedly in early pregnancy, prior to and independent of changes in insulin sensitivity. Circulating hormones may mediate this metabolic adaptation. Identifying mediators of this physiological effect could have therapeutic implications for treating hyperglycaemia during and outside of pregnancy.

Residual β cell function and monogenic variants in long-duration type 1 diabetes patients

BACKGROUNDIn the Joslin Medalist Study (Medalists), we determined whether significant associations exist between β cell function and pathology and clinical characteristics.METHODSIndividuals with type 1 diabetes (T1D) for 50 or more years underwent evaluation including HLA analysis, basal and longitudinal autoantibody (AAb) status, and β cell function by a mixed-meal tolerance test (MMTT) and a hyperglycemia/arginine clamp procedure. Postmortem analysis of pancreases from 68 Medalists was performed. Monogenic diabetes genes were screened for the entire cohort.RESULTSOf the 1019 Medalists, 32.4% retained detectable C-peptide levels (>0.05 ng/mL, median: 0.21 ng/mL). In those who underwent a MMTT (n = 516), 5.8% responded with a doubling of baseline C-peptide levels. Longitudinally (n = 181, median: 4 years), C-peptide levels increased in 12.2% (n = 22) and decreased in 37% (n = 67) of the Medalists. Among those with repeated MMTTs, 5.4% (3 of 56) and 16.1% (9 of 56) had waxing and waning responses, respectively. Thirty Medalists with baseline C-peptide levels of 0.1 ng/mL or higher underwent the clamp procedure, with HLA-/AAb- and HLA+/AAb- Medalists being most responsive. Postmortem examination of pancreases from 68 Medalists showed that all had scattered insulin-positive cells; 59 additionally had few insulin-positive cells within a few islets; and 14 additionally had lobes with multiple islets with numerous insulin-positive cells. Genetic analysis revealed that 280 Medalists (27.5%) had monogenic diabetes variants; in 80 (7.9%) of these Medalists, the variants were classified as "likely pathogenic" (rare exome variant ensemble learner [REVEL] >0.75).CONCLUSIONAll Medalists retained insulin-positive β cells, with many responding to metabolic stimuli even after 50 years of T1D. The Medalists were heterogeneous with respect to β cell function, and many with HLA+ diabetes risk alleles also had monogenic diabetes variants, indicating the importance of genetic testing for clinically diagnosed T1D.FUNDINGFunding for this work was provided by the Dianne Nunnally Hoppes Fund; the Beatson Pledge Fund; the NIH, National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK); and the American Diabetes Association (ADA).

Beta cells in type 1 diabetes: mass and function; sleeping or dead?

Histological analysis of donor pancreases coupled with measurement of serum C-peptide in clinical cohorts has challenged the idea that all beta cells are eventually destroyed in type 1 diabetes. These findings have raised a number of questions regarding how the remaining beta cells have escaped immune destruction, whether pools of 'sleeping' or dysfunctional beta cells could be rejuvenated and whether there is potential for new growth of beta cells. In this Review, we describe histological and in vivo evidence of persistent beta cells in type 1 diabetes and discuss the limitations of current methods to distinguish underlying beta cell mass in comparison with beta cell function. We highlight that evidence for new beta cell growth in humans many years from diagnosis is limited, and that this growth may be very minimal if at all present. We review recent contributions to the debate around beta cell abnormalities contributing to the pathogenesis of type 1 diabetes. We also discuss evidence for restoration of beta cell function, as opposed to mass, in recent-onset type 1 diabetes, but highlight the absence of data supporting functional recovery in the setting of long-duration diabetes. Finally, future areas of research are suggested to help resolve the source and phenotype of residual beta cells that persist in some, but not all, people with type 1 diabetes.

Higher Cord Blood Levels of Fatty Acids in Pregnant Women With Type 1 Diabetes Mellitus

CONTEXT

Type 1 diabetes mellitus (T1DM) is associated with a disturbance of carbohydrate and lipid metabolism.

OBJECTIVE

To determine whether T1DM alters maternal and neonatal fatty acid (FA) levels.

DESIGN

Observational study.

SETTING

Academic hospital.

PATIENTS

Sixty pregnant women (30 women with T1DM with good glycemic control and 30 healthy women) were included in the study. Maternal blood, umbilical vein, and artery blood samples were collected immediately upon delivery. Following lipid extraction, the FA profiles of the total FA pool of maternal serum and umbilical vein and artery serum were determined by gas chromatography.

RESULTS

Total FA concentration in maternal serum did not differ between the study groups; it was significantly higher in umbilical vein serum of the T1DM group compared with that in the control group [median (interquartile range)]: T1DM 2126.2 (1446.4 to 3181.3) and control 1073.8 (657.5 to 2226.0; P < 0.001), and in umbilical artery vein serum: T1DM 1805.7 (1393.1 to 2125.0) and control 990.0 (643.3 to 1668.0; P < 0.001). Composition of FAs in umbilical vein serum showed significantly higher concentrations of saturated, monounsaturated, and polyunsaturated FAs (SFAs, MUFAs, and PUFAs, respectively) in the T1DM group than compared with those in the control group (P = 0.001). Furthermore, cord blood levels of leptin (P < 0.001), C-peptide (P < 0.001), and insulin resistance (P = 0.015) were higher in the T1DM group compared with controls.

CONCLUSION

The neonates born to mothers with T1DM had higher concentrations of total FAs, SFAs and MUFAs, as well as PUFAs, compared with control newborns.

Parity Increases Insulin Requirements in Pregnant Women With Type 1 Diabetes

CONTEXT

Tight glycemic control throughout pregnancy in women with type 1 diabetes is crucial, and knowledge about which factors that affect insulin sensitivity could improve the outcome for both mother and offspring.

OBJECTIVE

To evaluate insulin requirements in women with type 1 diabetes during pregnancy and test whether parity affects insulin requirements.

DESIGN

Observational cohort study consisting of women with type 1 diabetes who gave birth at Aarhus University Hospital, Denmark, from 2004 to 2014.

MAIN OUTCOME MEASURE

Daily insulin requirement (the hypothesis that parity could affect insulin resistance was formulated before data collection).

RESULTS

A total of 380 women with a total of 536 pregnancies were included in the study. Mean age was 31.1 years, and prepregnancy hemoglobin A1c was 60 mmol/mol. Parity was as follows: P0, 43%; P1, 40%; P2, 14%; and P3+4, 3%. Insulin requirements from weeks 11 to 16 decreased significantly by 4% (P = 0.0004) and rose from week 19 to delivery with a peak of 70% (P < 0.0005) at weeks 33 to 36. Overall, insulin requirements increased significantly with parity. The unadjusted differences between P0 and P1, P2, and P3+4 were 9% (P < 0.0005), 12% (P < 0.0005), and 23% (P < 0.0011), respectively. After adjustment for confounders, differences were 13% (P < 0.0005), 20% (P < 0.0005), and 36% (P < 0.0005). We also observed an adjusted difference between P1 and P3+4 of 20% (P < 0.0012).

CONCLUSIONS

The data show changes in insulin requirements from week to week in pregnancy and indicate that insulin requirements increase with parity. This suggests that the patient's parity probably should be considered in choosing insulin dosages for pregnant women with type 1 diabetes.

The physiological and glycaemic changes in breastfeeding women with type 1 diabetes mellitus

The World Health Organisation recommends exclusive breastfeeding for the first six months of life (Australian institute of health and welfare, 2011). Breastfeeding confers many short- and long-term benefits for infants and mothers, including reduced childhood obesity and lower maternal body weight (Infant feeding survey, 2010; CDC National immunization surveys, 2012 and 2013; Sorkio et al., 2010; Hummel et al., 2014; Finkelstein et al., 2013). Exclusive breastfeeding is also recommended in women with type 1 diabetes mellitus (T1DM), for at least four months (Nucci et al., 2017). However, the impact of breastfeeding on mothers with T1DM, and, conversely, the impact of maternal T1DM on breastfeeding, is not clear. This review summarizes current knowledge regarding the epidemiology and physiology of breastfeeding in women with T1DM. In particular, it highlights the relationship between breastfeeding and glycaemia. Potential areas for future research are also identified.

Urinary C peptide creatinine ratio in pregnant women with normal glucose tolerance and type 1 diabetes: evidence for insulin secretion

HYPOTHESIS

In pregnancy, urinary C peptide creatinine ratio (UCPCR) reflects endogenous insulin secretion in women with normal glucose tolerance and type 1 diabetes.

RESEARCH DESIGN AND METHODS

UCPCR and serum C peptide were measured in 90 glucose-tolerant women at 0 and 120 min during a 75 g oral glucose tolerance test (OGTT) at 28 weeks of gestation. UCPCR was measured in 2 samples obtained over 10 weeks apart in 7 pregnant women with longstanding type 1 diabetes.

RESULTS

UCPCR_OGTT and serum C peptide_OGTT of glucose-tolerant women were significantly correlated at 0 and 120 min (r_s0.675, 0.541 respectively, p<0.0001). All 7 pregnant women with type 1 diabetes had detectable first sample UCPCR (median (range) 49 (6-1038) pmol/mmol) that rose in 6 women by 477 (29-1491) pmol/mmol.

CONCLUSIONS

Detectable UCPCR in pregnant women with normal glucose tolerance and type 1 diabetes is likely to reflect endogenous insulin secretion and hence β-cell activity.

Effect of pregnancy on insulin requirements differs between type 1 and type 2 diabetes: A cohort study of 222 pregnancies

BACKGROUND

Knowledge about expected insulin requirements during pregnancy, in women with pre-existing diabetes may assist clinicians to effectively respond to gestation-specific changes in glycemic pattern. Few studies have examined differences between type 1 (T1DM) and type 2 diabetes (T2DM).

AIMS

To compare patterns of insulin requirements in pregnancy for women with pre-existing T1DM and T2DM.

MATERIAL AND METHODS

A retrospective cohort study of 222 pregnancies was conducted in women with pre-existing diabetes, (67 with T1DM, 155 with T2DM). Total daily insulin dose (TID) at the end of each trimester, recorded as units and units per kilogram (median, 25th-75th percentile) as well as percentage increase in insulin dose per trimester were compared.

RESULTS

Women with T1DM had higher insulin requirements in the first two trimesters than those with T2DM (0.69 (0.58-0.85) vs 0.36 (0.0-0.7) units/kg in first trimester; 0.80 (0.62-0.95) vs 0.61 (0.27-0.95) units/kg, P < 0.005) in second trimester), but requirements in late pregnancy were similar (0.97 (0.69-1.29) vs 0.95 (0.53-1.32) units/kg, P = 0.54). Women with T2DM needed much greater increases in insulin per trimester compared to T1DM (P < 0.001). Women with T1DM had a net fall in insulin requirements (3.7% in the first trimester and 4.1% in the late third trimester) while those with T2DM did not.

CONCLUSIONS

This is the largest comparison study of insulin requirements in women with pre-existing diabetes, highlighting important trimester-specific differences between T1DM and T2DM to guide insulin titration during pregnancy. Our findings suggest a differential effect of pregnancy-mediated insulin resistance by type of diabetes.

Falling insulin requirements are associated with adverse obstetric outcomes in women with preexisting diabetes

OBJECTIVE

To investigate the clinical significance of falling insulin requirements in women with preexisting or overt diabetes in pregnancy.

RESEARCH DESIGN AND METHODS

A retrospective review of 139 pregnancies was conducted in women, with preexisting diabetes, delivering between January 2010 and January 2013. Women with falling insulin requirements of 15% or more from the peak total daily dose in late pregnancy were considered case subjects (n = 35). The primary outcome consisted of a composite of clinical markers of placental dysfunction, including preeclampsia, small for gestational age (SGA, ≤5th percentile for gestational age), stillbirth (>20 weeks), and premature delivery (≤30 weeks).

RESULTS

A total of 25.2% of women had >15% fall in insulin requirements with nulliparity as the only predictor at baseline (odds ratio [OR] 2.5 [95% CI 1.1-5.7], P = 0.03). Falling insulin requirements were associated with an increased risk of preeclampsia (OR 3.5 [1.1-10.7], P < 0.05) and the composite of clinical markers of placental dysfunction (4.4 [1.73-11.26], P = 0.002). Although falling insulin requirements were associated with higher rates of SGA (3.4 [1.0-11.3], P = 0.048), they were not associated with other adverse neonatal outcomes. However, there was a higher incidence of neonatal intensive care unit admission (15.5 [3.1-77.6], P = 0.001) and earlier delivery in this group (median 37.7 weeks [IQR 34.3-38.4] vs. 38.3 weeks [37.4-38.9], P = 0.014).

CONCLUSIONS

Falling insulin requirements, in women with preexisting diabetes, are associated with an increased risk of complications related to placental dysfunction. Further prospective studies are needed to guide clinical management.

Factors determining insulin requirements in women with type 1 diabetes mellitus during pregnancy: a review

Most women with type 1 diabetes mellitus (T1DM) have increased insulin requirements during pregnancy. However, a minority of women have a fall in insulin requirements. When this occurs in late gestation, it often provokes concern regarding possible compromise of the feto-placental unit. In some centres, this is considered as an indication for delivery, including premature delivery. There are, however, many other factors that affect insulin requirements in pregnancy in women with type 1 diabetes mellitus and the decline in insulin requirements may represent a variant of normal pregnancy. If there is no underlying pathological process, expedited delivery in these women is not warranted and confers increased risks to the newborn. We will explore the factors affecting insulin requirements in gestation in this review. We will also discuss some novel concepts regarding beta-cell function in pregnancy.

Maternal and fetal insulin levels at birth in women with polycystic ovary syndrome: data from a randomized controlled study on metformin

CONTEXT

Metformin is suggested to reduce pregnancy complications in women with polycystic ovary syndrome (PCOS). Metformin crosses the placenta and therapeutic concentrations are measured in the fetal circulation. Whether metformin treatment in pregnant PCOS women affects maternal and fetal insulin concentrations at birth is not clarified.

OBJECTIVES

To investigate the possible effect of metformin on insulin concentrations in umbilical cord blood and the possible association between maternal and fetal insulin concentrations.

DESIGN

Post-hoc analysis of a subgroup of PCOS women participating in a double-blind randomized controlled trial.

SETTING

University hospital setting.

PARTICIPANTS

Women with PCOS (n=118), aged 19-39 years.

MAIN OUTCOME MEASURES

Maternal and umbilical cord insulin concentrations immediately after birth.

RESULTS

At delivery women randomized to metformin had lower insulin concentrations than those randomized to placebo (259±209 vs 361±261 pmol/l; P=0.020). No difference was found in insulin concentrations in umbilical venous (P=0.95) and arterial (P=0.39) blood between the metformin and placebo groups. The arteriovenous difference was also equal between the groups (P=0.38). Insulin concentrations were higher in the umbilical vein than in the umbilical artery independent of randomization (70±51 vs 45±48 pmol/l; P<0.0005).

CONCLUSIONS

In PCOS, metformin treatment during pregnancy resulted in lower maternal insulin concentrations at delivery. Metformin treatment did not affect fetal insulin concentrations. Higher insulin concentrations in the umbilical vein indicate that the placenta somehow secretes insulin to the fetus. The possibility of placental insulin secretion to the fetus deserves further investigations.

The association between postprandial urinary C-peptide creatinine ratio and the treatment response to liraglutide: a multi-centre observational study

AIMS

The response to glucagon-like peptide 1 receptor agonist treatment may be influenced by endogenous β-cell function. We investigated whether urinary C-peptide creatinine ratio assessed before or during liraglutide treatment was associated with treatment response.

METHODS

A single, outpatient urine sample for urinary C-peptide creatinine ratio was collected 2 h after the largest meal of the day among two separate groups: (1) subjects initiating liraglutide (0.6 → 1.2 mg daily) or (2) subjects already treated with liraglutide for 20-32 weeks. The associations between pretreatment and on-treatment urinary C-peptide creatinine ratio and HbA1c change at 32 weeks were assessed using univariate and multivariate analyses (the ratio was logarithm transformed for multivariate analyses). Changes in HbA1c according to pretreatment urinary C-peptide creatinine ratio quartiles are shown.

RESULTS

One hundred and sixteen subjects (70 pretreatment, 46 on treatment) with Type 2 diabetes from 10 diabetes centres were studied. In univariate analyses, neither pretreatment nor on-treatment urinary C-peptide creatinine ratio correlated with HbA1c change (Spearman rank correlation coefficient, r = -0.17, P = 0.17 and r = -0.20, P = 0.19, respectively). In multi-linear regression analyses, entering baseline HbA1c and log urinary C-peptide creatinine ratio, pretreatment and on-treatment log urinary C-peptide creatinine ratio became significantly associated with HbA1c change (P = 0.048 and P = 0.040, respectively). Mean (sd) HbA1c changes from baseline in quartiles 1 to 4 of pretreatment urinary C-peptide creatinine ratio were -3 ± 17 mmol/mol (-0.3 ± 1.6%) (P = 0.52), -12 ± 15 mmol/mol (-1.1 ± 1.4%) (P = 0.003), -11 ± 13 mmol/mol (-1.0 ± 1.2%) (P = 0.002) and -12±17 mmol/mol (-1.1±1.6%) (P=0.016), respectively.

CONCLUSIONS

Postprandial urinary C-peptide creatinine ratios before and during liraglutide treatment were weakly associated with the glycaemic response to treatment. Low pretreatment urinary C-peptide creatinine ratio may be more useful than higher values by predicting poorer glycaemic response.

Residual C-peptide in type 1 diabetes: what do we really know?

Connecting peptide, or C-peptide, is a protein that joins insulin's α and B chains in the proinsulin molecule. During insulin synthesis, C-peptide is cleaved from proinsulin and secreted in an equimolar concentration to insulin from the β cells. Because C-peptide experiences little first-pass clearance by the liver, and because levels are not affected by exogenous insulin administration, it may be used as a marker of endogenous insulin production and a reflection of β-cell function. Residual β-cell function, as measured by C-peptide in those with type 1 diabetes (T1D), has repeatedly been demonstrated to be clinically important. The Eisenbarth model of type 1 diabetes postulated immune-mediated linear loss of β cells, with clinical diagnosis occurring when there was insufficient insulin secretion to meet glycemic demand. Moreover, the model also implied that all individuals with T1D rapidly and inevitably progressed to absolute insulin deficiency. Correspondingly, it was assumed that most people with longstanding T1D would show little to no residual C-peptide secretion. While more than a quarter century of data confirms that this model remains largely true and appropriately serves as the basis for prevention studies, accumulating evidence suggests that the natural history of β-cell function before, during and after diagnosis is more complex. In this review, we discuss the clinical benefits of residual insulin secretion and present recent data about the natural history of insulin secretion in those with, or at risk for T1D.

Peripartum management of glycemia in women with type 1 diabetes

OBJECTIVE

We aimed to 1) describe the peripartum management of type 1 diabetes at an Australian teaching hospital and 2) discuss factors influencing the apparent transient insulin independence postpartum.

RESEARCH DESIGN AND METHODS

We conducted a retrospective review of women with type 1 diabetes delivering singleton pregnancies from 2005 to 2010. Information was collected regarding demographics, medical history, peripartum management and outcome, and breast-feeding. To detect a difference in time to first postpartum blood glucose level (BGL) >8 mmol/L between women with an early (<4 h) and late (>12 h) requirement for insulin postpartum, with a power of 80% and a type 1 error of 0.05, at least 24 patients were required.

RESULTS

An intravenous insulin infusion was commenced in almost 95% of women. Univariate analysis showed that increased BMI at term, lower creatinine at term, longer duration from last dose of long- or intermediate-acting insulin, and discontinuation of an insulin infusion postpartum were associated with a shorter time to first requirement of insulin postpartum (P = 0.005, 0.026, 0.026, and <0.001, respectively). There was a correlation between higher doses of insulin commenced postpartum and number of out-of-range BGLs (r[36] = 0.358, P = 0.030) and hypoglycemia (r[36] = 0.434, P = 0.007). Almost 60% had at least one BGL <3.5 mmol/L between delivery and discharge.

CONCLUSIONS

Changes in the pharmacodynamic profile of insulin may contribute to the transient insulin independence sometimes observed postpartum in type 1 diabetes. A dose of 50-60% of the prepregnancy insulin requirement resulted in the lowest rate of hypoglycemia and glucose excursions. These results require validation in a larger, prospective study.

Addition of exenatide or sitagliptin to insulin in new onset type 1 diabetes: a randomized, open label study

Incretin based therapies are known to have pleotropic benefits in type 2 diabetes but have not been studied in new onset type 1 diabetes. In this randomized, open label study, we investigated the effect of the addition of exenatide or sitagliptin to insulin in patients with new onset type 1 diabetes. Our data suggest that the addition of exenatide and sitagliptin decreases insulin requirements without increasing endogenous insulin production and hypoglycemic events.

Impaired hormonal counterregulation to biochemical hypoglycaemia does not explain the high incidence of severe hypoglycaemia during pregnancy in women with type 1 diabetes

AIMS

To explore hormonal counterregulation to biochemical hypoglycaemia during pregnancy.

METHODS

Observational study of 107 consecutive pregnant women with type 1 diabetes (median duration 16 years (range 1-36), HbA1c 6.6% (4.9-10.5) in early pregnancy) and 22 healthy pregnant women. At 8, 14, 21, 27 and 33 weeks (women with diabetes) and 15, 28 and 34 weeks (healthy women) blood was sampled for measurements of glucose, adrenaline, noradrenaline, cortisol and glucagon. Each woman's measurement of serum glucose was matched with her corresponding hormone concentrations. Severe hypoglycaemia (requiring help from another person) was recorded prospectively.

RESULTS

During normoglycaemia (serum glucose > 3.9 mmol/L), adrenaline concentrations were higher in early pregnancy compared with late pregnancy in women with diabetes (21 (7-111) pg/ml vs. 17 (2-131), p = 0.02) and healthy women (21 (10-37) pg/ml vs. 13 (5-49), p = 0.046). Biochemical hypoglycaemia (serum glucose ≤ 3.9 mmol/L) occurred in 70 women with diabetes (65%) in at least one of the five samplings. At 8 and 33 weeks, adrenaline concentrations at biochemical hypoglycaemia were similar (30 (5-164) pg/ml and 29 (9-152), p = 0.79). Adrenaline concentrations at biochemical hypoglycaemia increased from normoglycaemia at diabetes duration < 16 years (p = 0.03). In first trimester, adrenaline concentrations were comparable in women with or without severe hypoglycaemia (24 (14-164) pg/ml vs. 33 (5-86), p = 0.35). Noradrenaline, glucagon and cortisol concentrations did not increase during biochemical hypoglycaemia.

CONCLUSION

Adrenaline response to biochemical hypoglycaemia was present at similar levels in early and late pregnancy, particularly in shorter diabetes duration, and was not associated with severe hypoglycaemia in early pregnancy.

Insulin requirements in late pregnancy in women with type 1 diabetes mellitus: a retrospective review

Pregnancy in women with type 1 diabetes mellitus (T1DM) is generally associated with increased insulin requirements.

AIMS

To determine the frequency and significance of declining insulin requirements in late gestation in women with T1DM.

METHODS

We conducted a retrospective review of 54 women seen at our institution from 2006 to 2010 with a diagnosis of T1DM pre-pregnancy and presentation for antenatal care prior to 28 weeks. Information was collected regarding patient demographics, insulin dose and pregnancy outcome. A 15% difference in weight-adjusted basal insulin from 30 weeks gestation to delivery was considered significant.

RESULTS

Five women (9.3%) had a fall of 15% or more and 23 (42.5%) had a rise of 15% or more rise in insulin requirements. There were fewer neonatal intensive care admissions but more infants with an APGAR <8 at 5 min in women with a fall in insulin requirements. These differences were not evident when the data were re-analysed by quartiles of change.

CONCLUSIONS

In most women with T1DM, insulin requirements show little change from 30 weeks gestation until delivery. Almost 10% of women had a significant fall in insulin requirements which did not correlate with adverse neonatal outcome. These results require validation in a larger, prospective trial.

Plasma C-peptide concentration in women with Type 1 diabetes during early and late pregnancy

AIMS

There are previous suggestions of increased C-peptide concentration in women with Type 1 diabetes during pregnancy. Our aim was to re-evaluate the hypothesis of a pregnancy-induced increase by measuring plasma C-peptide concentration in women with stable blood glucose control under standardized fasting and meal-stimulated conditions.

METHODS

Ten women with Type 1 diabetes; median age 31.1 years, median diabetes duration 19 years, median HbA(1c) 52 mmol/mol (6.9%) were admitted to a clinical research facility for two 24-h visits in early (12-16 weeks) and late (28-32 weeks) pregnancy. Women They ate standardized study meals - 80-g carbohydrate dinner, 60-g carbohydrate breakfast, and fasted between meals and overnight. Closed-loop insulin delivery maintained stable and comparable glycaemic conditions. Paired samples for plasma glucose and C-peptide were obtained.

RESULTS

Plasma glucose levels were comparable in early (median 6.5 mmol/l; interquartile range 5.6-8.6) and late pregnancy (median 7.0 mmol/l; interquartile range 6.1-7.8; P = 0.72). There was no change in fasting or meal-stimulated plasma C-peptide concentration from early to late pregnancy; mean difference 4.0 pmol/l (95% CI -6.0 to 7.0; P = 0.9). Four women had detectable C-peptide; peak (range) early vs. late pregnancy 48.5 (10-115) vs. 40.0 pmol/l (80-105); P = 0.5, which was weakly associated with plasma glucose; R(2) = 0.15, P < 0.0001.

CONCLUSIONS

We found no gestational changes in plasma C-peptide concentration. Previously reported increases may reflect differences in glucose control and/or exogenous insulin doses. This study highlights the importance and challenges of standardizing experimental conditions for accurate plasma C-peptide measurement during Type 1 diabetes pregnancy.

Lactogens protect rodent and human beta cells against glucolipotoxicity-induced cell death through Janus kinase-2 (JAK2)/signal transducer and activator of transcription-5 (STAT5) signalling

AIMS/HYPOTHESIS

A leading cause of type 2 diabetes is a reduction in functional beta cell mass partly due to increased beta cell death, triggered by stressors such as glucolipotoxicity (GLT). This study evaluates the hypothesis that lactogens can protect beta cells against GLT and examines the mechanism behind the pro-survival effect.

METHODS

The effect of exogenous treatment or endogenous expression of lactogens on GLT-induced beta cell death was examined in INS-1 cells, and in rodent and human islets. The mechanism behind the pro-survival effect of lactogens was determined using an inhibitor, siRNAs, a dominant negative (DN) mutant, and Cre-lox-mediated gene deletion analysis.

RESULTS

Lactogens significantly protect INS-1 and primary rodent beta cells against GLT-induced cell death. The pro-survival effect of lactogens in rodent beta cells is mediated through activation of the Janus kinase-2 (JAK2)/signal transducer and activator of transcription-5 (STAT5) signalling pathway. Lactogen-induced increase in the anti-apoptotic B cell lymphoma-extra large (BCLXL) protein is required to mediate its pro-survival effects in both INS-1 cells and primary rodent beta cells. Most importantly, lactogens significantly protect human beta cells against GLT-induced cell death, and their pro-survival effect is also mediated through the JAK2/STAT5 pathway.

CONCLUSIONS/INTERPRETATION

These studies, together with previous work, clearly demonstrate the pro-survival nature of lactogens and identify the JAK2/STAT5 pathway as an important mediator of this effect in both rodent and human beta cells. Future studies will determine the effectiveness of this peptide in vivo in the pathophysiology of type 2 diabetes.

Hypoglycaemia during pregnancy in women with Type 1 diabetes

AIMS

To explore incidence, risk factors, possible pathophysiological factors and clinical management of hypoglycaemia during pregnancy in women with Type 1 diabetes.

METHODS

Literature review.

RESULTS

In women with Type 1 diabetes, severe hypoglycaemia occurs three to five times more frequently in early pregnancy than in the period prior to pregnancy, whereas in the third trimester the incidence of severe hypoglycaemia is lower than in the year preceding pregnancy. The frequency distribution of severe hypoglycaemia is much skewed, as 10% of the pregnant women account for 60% of all recorded events. Risk factors for severe hypoglycaemia during pregnancy include a history with severe hypoglycaemia in the year preceding pregnancy, impaired hypoglycaemia awareness, long duration of diabetes, low HbA(1c) in early pregnancy, fluctuating plasma glucose values (≤ 3.9 mmol/l or ≥ 10.0 mmol/l) and excessive use of supplementary insulin injections between meals. Pregnancy-induced nausea and vomiting seem not to be contributing factors.

CONCLUSIONS

Striving for near-normoglycaemia with focus on reduction of plasma glucose fluctuations during pregnancy should have high priority among clinicians with the persistent aim of improving pregnancy outcome among women with Type 1 diabetes. Pre-conception counselling, carbohydrate counting, use of insulin analogues, continuous subcutaneous insulin infusion (insulin pump) therapy and real-time continuous glucose monitoring with alarms for low glucose values might be relevant tools to obtain near-normoglycaemia without episodes of severe hypoglycaemia.

Adaptive changes in pancreatic beta cell fractional area and beta cell turnover in human pregnancy

AIMS/HYPOTHESIS

We sought to establish the extent and basis for adaptive changes in beta cell numbers in human pregnancy.

METHODS

Pancreas was obtained at autopsy from women who had died while pregnant (n = 18), post-partum (n = 6) or were not pregnant at or shortly before death (controls; n = 20). Pancreases were evaluated for fractional pancreatic beta cell area, islet size and islet fraction of beta cells, beta cell replication (Ki67) and apoptosis (TUNEL), and indirect markers of beta cell neogenesis (insulin-positive cells in ducts and scattered beta cells in pancreas).

RESULTS

The pancreatic fractional beta cell area was increased by approximately 1.4-fold in human pregnancy, with no change in mean beta cell size. In pregnancy there were more small islets rather than an increase in islet size or beta cells per islet. No increase in beta cell replication or change in beta cell apoptosis was detected, but duct cells positive for insulin and scattered beta cells were increased with pregnancy.

CONCLUSIONS/INTERPRETATION

The adaptive increase in beta cell numbers in human pregnancy is not as great as in most reports in rodents. This increase in humans is achieved by increased numbers of beta cells in apparently new small islets, rather than duplication of beta cells in existing islets, which is characteristic of pregnancy in rodents.

Onset of autoimmune type 1 diabetes during pregnancy: Prevalence and outcomes

Although this has been recently challenged, gestational diabetes mellitus (gestational diabetes) is still defined as an "impairment of glucose tolerance with onset or first recognition during pregnancy". According to this definition, all pathophysiological conditions leading to beta cell deficiency may reveal as gestational diabetes, due to the physiological insulin resistance associated with pregnancy. In rare patients, gestational diabetes is associated with the presence of islet autoantibodies and with a high risk of progression to overt type 1 diabetes after delivery. This condition has often been compared to the Latent Autoimmune Diabetes in Adults. The frequency of islet autoantibodies in gestational diabetes has been assessed in many studies, but data about the clinical presentation of this subtype and about its prognosis are few. We review these studies and discuss the links of autoimmune gestational diabetes with type 1 diabetes mellitus.

Insulin requirements throughout pregnancy in women with type 1 diabetes mellitus: three changes of direction

AIMS/HYPOTHESIS

The aim of the study was to analyse the insulin requirements of women with type 1 diabetes mellitus throughout pregnancy.

METHODS

We have examined the weekly mean blood glucose (mmol/l), insulin requirements (U kg(-1) day(-1)) and total insulin requirements (U/day) in 65 women with type 1 diabetes mellitus and tight metabolic control since before pregnancy (HbA(1c) < or =6.0%).

RESULTS

Both insulin requirement and total insulin requirement displayed a peak in week 9, a nadir in week 16 and a second peak in week 37. For the change in insulin requirement (4.08% per week) and in total insulin requirement (5.19% per week), the sharpest slope was observed from week 16 to week 37. However, two changes of direction took place in the first 11 weeks and eight out of nine episodes of severe hypoglycaemia requiring treatment with glucagon or i.v. glucose took place in the first 16 weeks.

CONCLUSIONS/INTERPRETATION

Pregnant women with type 1 diabetes mellitus and tight metabolic control since before pregnancy displayed changes in insulin requirement and total insulin requirement with successive changes of direction. The sharpest slope was observed between 16 and 37 weeks, but insulin requirements were more unstable in the first 16 weeks. This information could help patients and physicians to react to changes in glycaemic pattern in a prompt and adequate way.

Type 1 diabetes mellitus and pregnancy

Diabetes complicates up to 10% of all pregnancies in the United States. Of these, 0.2% to 0.5% are patients with type 1 diabetes mellitus (T1DM). Pregnancies affected by T1DM are at increased risk for preterm delivery, preeclampsia, macrosomia, shoulder dystocia, intrauterine fetal demise, fetal growth restriction, cardiac and renal malformations, in addition to rare neural conditions such as sacral agenesis. Intensive glycemic control and preconception planning have been shown to decrease the rate of fetal demise and malformations seen in pregnancies complicated by T1DM. Recent advances in insulin formulations and delivery methods have increased the number of options available to the obstetric team. Insulin regimens should be tailored to each individual patient to maximize compliance and ensure proper glycemic control. Intensive preconception counseling with frequent follow-up visits emphasizing tight glucose control is recommended for adequate management.