β-Cell adaptation to maternal insulin resistance of pregnancy involves upregulation of β-cell mass and function, a process we previously showed depends on prolactin receptor (PRLR) signaling. Emerging evidence in humans suggests that prolactin signaling may also influence β-cell function beyond pregnancy. This study aims to investigate how postpregnancy metabolic stress-specifically the combined effects of prior pregnancy followed by high-fat diet (HFD) exposure-impacts β-cell function, with a focus on the role of PRLR. In this study, we found that multiparous transgenic female mice with β-cell-specific PRLR deletion (βPrlr-/-) have impaired glucose tolerance when challenged with HFD. Unlike in pregnancy, where PRLR signaling upregulates β-cell proliferation and mass, we observed no difference in β-cell mass between the wild-type (βPrlr+/+) and mutant (βPrlr-/-) mice when metabolically stressed with HFD. However, βPrlr-/- mice showed blunted first-phase insulin release in vivo when challenged with glucose orally but not intraperitoneally, suggesting an impaired incretin effect. Moreover, there is a reduction in the expression of incretin hormone receptor, Glp-1r, and several of its upstream regulators, such as E2f1, Nkx6.1, Pax6, Pparγ, and Tcf7l2. Interestingly, isolated islets from βPrlr-/- mice showed intact in vitro glucose-stimulated insulin secretion (GSIS) but impaired incretin-potentiated GSIS. Islets from βPrlr-/- mice also had a lower insulin content and expressed lower levels of genes that regulate glucose metabolism. Together, these results suggested that PRLR signaling plays an important role in preserving β-cell function in mice exposed to metabolic stress by maintaining incretin receptor expression and insulin secretory capacity in β-cells.NEW & NOTEWORTHY Prolactin receptor (PRLR) signaling is crucial for β-cell adaptation to metabolic stresses from repeated pregnancies compounded by a high-fat diet (HFD). In PRLR-deficient β-cells, there is a reduction in insulin synthesis, expression of the gene that regulates GSIS, and incretin receptor Glp1r expression and response. This results in lower insulin secretion and impaired glucose tolerance. The link between PRLR and incretin receptor expression and function in islets is novel.

During pregnancy, pancreatic β-cell mass and function are increased in adaptation to insulin resistance; this requires the action of prolactin receptor signaling. Recently, we discovered the Lrrc55, an auxiliary subunit of the voltage- and calcium-activated potassium channel (BK channel), is a prosurvival factor in β-cell, and its expression and highly and specifically up regulated in the pancreatic islets during pregnancy. We found that overexpression of Lrrc55 protects β-cells from glucolipotoxicity (GLT)-induced apoptosis. The protective effect of Lrrc55 is associated with dampening of the ER stress response and preservation of the releasable pool of calcium in the ER. Thus, we hypothesized that Lrrc55 protects β-cells from GLT-induced ER stress and apoptosis by regulating ER calcium handling. Here, we report that Lrrc55 restored the GLT-mediated decrease in expression levels the insulin regulators, Pdx-1 and MafA , as well as the ER calcium regulator SERCA. Lrrc55 also attenuated the GLT-induced increase in expression of the ER calcium channel RyR2. Lrrc55 also attenuated GLT-mediated increase in protein expression of pro-apoptotic molecules CHOP and IRE1α, and increased activation of the anti-apoptotic molecule Akt. However, Lrrc55 does not alter the activity levels of SERCA or IP3R under physiologic conditions. Transgenic mice with global deletion of Lrrc55 (Lrrc55−/−) are more susceptible to streptozotocin-induced diabetes. Surprisingly, Lrrc55−/− mice are more glucose tolerant and secreted more insulin during pregnancy. Together, these results suggest a role for Lrrc55 in maintaining expression of the ER calcium regulators in the presence of GLT but it may negatively regulate insulin secretion. ### Competing Interest Statement The authors have declared no competing interest. Natural Sciences and Engineering Research Council of Canada, RGPIN-2020-05247

Introduction Type 1 diabetes (T1D) mellitus is caused by autoimmune destruction of insulin-producing beta-cells, requiring exogenous insulin to sustain life. Achieving near normal blood glucose levels with insulin, a primary goal of diabetes management, carries a significant risk of hypoglycaemia. There is compelling evidence that an abnormal gut microbiota or dysbiosis can increase intestinal permeability (IP) and contribute to dysglycaemia seen in T1D. Given that prebiotic fibre can mitigate dysbiosis, reduce IP and improve glycaemic control, we hypothesise that microbial changes induced by prebiotics contribute to gut and endocrine adaptations that reduce glucose fluctuations, including less hypoglycaemia. In a pilot study, we showed that in children who had T1D for at least 1 year, a 3-month course of prebiotic fibre significantly reduced the frequency of hypoglycaemia. The prebiotic group had an increase in Bifidobacterium with a moderate improvement in IP. Importantly, the prebiotic group maintained their serum C peptide level (marker of residual beta cell function) while the placebo group saw a drop. Given that preserving endogenous beta cell function in patients with T1D, particularly in the first year of diagnosis, reduces hypoglycaemia and glycaemic variability, we propose to examine the effect of prebiotic supplementation in patients with T1D.Methods and analysis This is a multicentre, randomised, double-blind, placebo-controlled study. Individuals (n=144) with T1D will be randomised 1:1 for 6 months to prebiotic (oligofructose-enriched inulin) or placebo (isocaloric maltodextrin). Participants will have three in-person study visits at baseline, 3 months and 6 months. The primary outcome, frequency of hypoglycaemia, will be determined from continuous glucose monitor (CGM) reports and patient blood glucose logs. Secondary outcomes will include glycaemic variability, time-in-range, glycated haemoglobin, stimulated C peptide, IP, serum inflammatory markers, quality of life and fear of hypoglycaemia ratings, as well as gut microbiome and metabolomics analysis. At 9 months, participant CGM data will be used to assess frequency of hypoglycaemia and glycaemic variability at 3 months postintervention.Ethics and dissemination The study received ethical approval from the University of Calgary Conjoint Health Research Ethics Board (REB21-0852). The University of Alberta subsite was granted ethical approval under the province of Alberta’s research ethics reciprocity agreement as a participating site (REB21-0852; pSite00000066). The University of Saskatchewan subsite was granted ethical approval by the Biomedical Research Ethics Board (#4149). Trial findings will be disseminated through peer-reviewed publications and conference presentations.Trial registration number clinicaltrials.gov NCT04963777.

The role of prolactin receptor (PRLR) signaling in β-cell adaptation to maternal insulin resistance of pregnancy has been well demonstrated. Using transgenic mice with an inducible β-cell-specific Prlr deletion (βPrlr-/-), we found that intact PRLR, as found in βPrlr+/+ mice, were protected from developing glucose intolerance during pregnancy, and the main mechanism responsible for this PRLR-mediated effect is the up regulation of β-cell proliferation and insulin synthesis. Interestingly, studies in male mice and humans have found a link between diminished PRLR signaling and abnormal β-cell function. We aimed to determine whether PRLR has a role in regulating β-cell function outside of pregnancy, protecting β-cell against exposure to metabolic stressors.In this study, we found that β-cell-specific PRLR reduction resulted in impaired glucose tolerance in multiparous female mice challenged with a 12-week course of high-fat diet (HFD). Unlike in pregnancy, where PRLR signaling up regulates β-cell proliferation resulting in a greater β-cell mass, we observed no difference in β-cell mass between the wild type (βPrlr+/+) and mutant (βPrlr-/-) mice. In vitro glucose-stimulated insulin secretion using isolated islets from wild type (βPrlr+/+) and mutant (βPrlr-/-) mice showed comparable insulin response, but βPrlr-/- mice showed blunted first-phase insulin release in vivo, although only when challenged with glucose orally and not intraperitoneally, suggesting an impairment of the incretin effect. In support of the observed defect in incretin action, we found a reduction in expression of both incretin hormone receptors, Gipr and Glp-1r , and several of their upstream regulators, such as E2f1, Nkx6 . 1, Pax6, Pparγ , and Tcf7l2 . Islets from the mutant mice also have a lower insulin content and reduced levels of genes that regulate glucose metabolism. Together, these results suggested that PRLR signaling plays an important role in preserving β-cell function in mice exposed to metabolic stress by maintaining incretin receptor expression and insulin secretory capacity in β cells.### Competing Interest StatementThe authors have declared no competing interest.

Environmental risk factors possess the potential to modulate the pathogenesis of type I diabetes (T1D). Foremost among these factors are early life influences impacting the gastrointestinal (GI) tract. During infancy, both the microbiota and immune system are influenced by maternal factors contributing to key events in the neonatal GI tract. Despite the well-known importance of maternal factors on infant immune development, whether maternal immune dysregulation and dysbiosis can perpetuate the same in offspring remains largely unknown. To explore how these maternal factors impact offspring disease development, we used IgA-deficiency induced maternal dysbiosis in Non-Obese Diabetic (NOD) dams to study T1D development in their progeny. We found that maternal dysbiosis led to changes in IgA-sufficient offspring immune development resulting in heightened GI immune activity. Maternal dysbiosis also contributed to altered microbiome establishment in progeny, such that pups exhibited reduced colonic abundance of Akkermansia muciniphila and Clostridoides difficile. In adulthood, these mice exhibited a lowered incidence of T1D. This protection was replicated by fostering high incidence offspring to dysbiotic dams, prompting us to propose that altered breast milk composition in dysbiotic dams can influence immune development and microbiome establishment in offspring, contributing to T1D resistance. ### Competing Interest Statement The authors have declared no competing interest.

OBJECTIVES:This study aimed to employ big data analysis to harmonize reference intervals (RI) for thyroid function tests, with refinement to the TSH upper reference limit, and to optimize the TSH reflex algorithm to improve clinical management and test utilization. DESIGN & METHODS:TSH, free T4, and free T3 results tested in Alberta, Canada, on Roche Cobas and Siemens Atellica were extracted from the laboratory information system (N = 1,144,155 for TSH, N = 183,354 for free T4 and N = 92,632 for free T3). Results from specialists, inpatients, or repeat testing, as well as from positive thyroid disease, autoimmune disease, and pregnancy biomarkers were excluded. RIs were derived using statistical models (Bhattacharya, refineR, and simple non-parametric) followed by endocrinology and laboratory review. RESULTS:The TSH RIs for 0 to 7 days, 8 days to 1 year, and ≥1 year were 1.23 to 25.0 mIU/L, 1.00 to 6.80 mIU/L and 0.20 to 6.50 mIU/L, respectively. The free T4 RIs for 0 to 14 days, 15 to 29 days, and ≥30 days were 13.5 to 50.0 pmol/L, 8.7 to 32.5 pmol/L, and 10.0 to 25.0 pmol/L, respectively. An updated TSH reflex algorithm was developed based on the optimized TSH and free T4 RIs, with free T4 reflexed only at a TSH of <0.1 mIU/L. CONCLUSIONS:The collaboration of a multidisciplinary team and the utilization of big data analysis led to the enhancement of thyroid function RIs, specifically resulting in the widening of the upper TSH reference limit to 6.50. Application of these optimized RIs with the TSH reflex algorithm will serve as a guide for improvement in interpretation of thyroid function tests.

Infants born to mothers with type 2 diabetes (T2D) and gestational diabetes (GDM) are at an increased risk of being overweight/obese. Modifiable lifestyle factors play a role in prevention of overweight and obesity. In 2017, the Canadian 24 h Movement Guidelines for the Early Years (CMG) were released. Alongside physical activity recommendations, sweetened beverage consumption (SBC) recommendations were also released by the American Academy of Pediatrics in 2017. The objective of this study was to determine the knowledge pregnant women with T2D and GDM have on the CMG and SBC recommendations, and to determine what factors affect this. A survey with questions regarding demographics, socioeconomic variables and the CMG and SBC recommendations was administered to pregnant women at Diabetes in Pregnancy clinics in Calgary, Alberta from July 2019 to January 2020. Surveys were analyzed utilizing the non-parametric Kruskall-Wallis Rank-Sum test, chi-square test and linear regression. A total of 79 respondents with T2D and GDM were collected. Respondents had the highest knowledge of SBC recommendations and the lowest knowledge of CMG recommendations. A bachelor's or higher degree was associated with significantly higher knowledge scores than a high-school education or less. In conclusion, pregnant women with T2D and GDM in this study had overall poor knowledge of the CMG and SBC recommendations, with less knowledge regarding the CMG. Level of education was found to be associated with knowledge regarding these recommendations. Future programs to improve education around infant and toddler physical activity and SBC recommendations may be beneficial for this patient population.

Abstract Background Children with growth hormone deficiency (GHD) are treated with recombinant human growth hormone (rhGH), usually administered as a daily subcutaneous injection. Long-acting hGH (LAGH) treatments (approved and in development) have the potential to improve adherence and treatment outcomes. Somatrogon is a LAGH currently being developed as a once-weekly injectable treatment for GHD. The Pfizer Registry of Outcomes in Growth hormone RESearch (PROGRES) study was initiated to assess the long-term safety and effectiveness of Genotropin and other hGH formulations to treat GHD under routine clinical care. Goals & aims: The overall goal of the registry is to increase our understanding of hGH treatments as used in a real-world setting. Enrolling children treated with different daily hGH brands as well as somatrogon (if approved in a given geography) will enable comparison between daily and LAGH, and across daily hGH brands. The primary objectives of the study are to describe and compare the safety and effectiveness of daily and LAGH treatments in children. Secondary objectives include evaluating adherence to hGH treatments and the health-related quality of life (HRQoL) and treatment experience of patients receiving hGH treatments. Methods For this non-interventional, prospective, phase 4 cohort study, eligible patients (male or female at any age) from >20 countries are planned for inclusion, with the aim of targeting 667 patients across the daily hGH brands in each of the three geographic regions. Patients will be enrolled from September 2021 to October 2029, with data collection planned until October 2030. Study inclusion criteria include prescription of daily Genotropin or other approved hGH treatments for GHD and the provision of informed consent/assent. If somatrogon is approved by regulatory agencies, somatrogon-treated patients will also be eligible for inclusion. Patients participating in any interventional clinical trials at the time of enrollment will be excluded from the study. Patients will be followed until the end of the study, withdrawal of consent, death, switch to an excluded hGH, or loss to follow-up, whichever occurs first. In addition to demographic and clinical characteristics, information on hGH treatment brand, dose and start/end dates will be collected, along with reasons for switching or discontinuing treatment. Primary safety outcomes include adverse events (AEs), serious AEs, and AEs of special interest. Primary effectiveness outcomes include annual height velocity (HV) and change in HV standard deviation scores. Treatment adherence, compliance outcomes, HRQoL, and patient treatment experience will be assessed. Conclusions The findings from the PROGRES study will provide valuable insights into the use of somatrogon, Genotropin and other approved hGH treatments in real-world clinical practice, specifically with regard to the long-term safety and effectiveness of these treatments as well as treatment compliance and patient HRQoL. Presentation: Monday, June 13, 2022 12:30 p.m. - 2:30 p.m.

The ability of β cells. to adapt to metabolic stressors is important in preventing diabetes. Our lab has previously shown that prolactin receptor (Prlr) signalling is required for β-cell adaptation to insulin resistance of pregnancy, mainly by regulating β-cell proliferation. Whether Prlr signalling is important for β-cell adaptation to physiologic stresses other than pregnancy is unknown. This study aimed to determine whether Prlr signalling is required for β-cell adaptation to the cumulative stresses of pregnancies followed by exposure to a high fat diet (HFD), a commonly observed scenario in humans.