Mohan, Sneha

Hyperglycemia in prediabetes is accompanied by increased amino acid (AA) concentrations and impaired suppression of glucagon secretion by glucose. It is unknown whether an abnormal response to AA contributes or hepatic steatosis exacerbates α-cell dysfunction. Therefore, lean participants and participants with obesity (with and without hepatic steatosis) were studied on two occasions in random order using a graded glucose infusion. Saline or an AA mixture was infused. The glucagon secretion rate (GSR) was derived from peripheral glucagon concentrations, and the change in glucose required to reduce GSR by 50% (G50) was calculated for each participant. AAs were measured during the experiment. On both occasions, experimental conditions produced a progressive rise in insulin secretion and an inverse exponential suppression of glucagon. G50 did not differ between groups in response to glucose alone. AA infusion did not change G50 in lean participants. G50 increased during AA infusion in participants with obesity with and without hepatic steatosis, leading us to report these participants as a single group. The relative change in AA concentrations across study days was generally similar between groups. We conclude that despite a normal response to glucose, obesity increases α-cell responses to AA in humans. Article Highlights The aim of this study was to understand the pathogenesis of α-cell dysfunction in prediabetes. The primary hypothesis was that α-cell responsivity to glucose (reduction of the glucagon secretion rate by 50%) is impaired by amino acid (AA) infusion. A secondary hypothesis was that this abnormal response is exacerbated by hepatic steatosis. AA infusion impaired α-cell suppression in response to rising glucose in participants with obesity, but not in lean participants, despite a normal response to glucose alone. This abnormal response was unaffected by the presence or absence of hepatic steatosis. It seems likely that an abnormal α-cell response to AAs precedes an abnormal response to glucose alone.

Background: Pregnancy in teenagers and emerging adults is associated with an increased risk of adverse outcomes. Similarly, pregnancies complicated by pregestational and gestational diabetes mellitus (GDM) carry a higher risk of complications. However, limited data exist on the intersection of these two high-risk conditions. Our objective was to establish the prevalence of teenage and emerging adult pregnancies complicated by diabetes in a population-based cohort and compare outcomes to pregnancies uncomplicated by diabetes, noting a background prevalence of GDM of 8.1% and pregestational diabetes of 1.2% across all age groups in the United States. Methods: This is a retrospective cohort study conducted in Olmsted County, Minnesota, USA. It includes female residents aged ≤21 years with a pregnancy ICD-10 code between January 1, 2013, and December 31, 2022. The main outcome measures assessed include maternal characteristics and maternal and fetal pregnancy outcomes. Results: A total of 1491 pregnancies in 1379 individuals were identified and included. In total, 68 (4.6%) pregnancies were complicated by diabetes: 51 (3.4%) with GDM and 17 (1.1%) with pregestational diabetes. In this study, pregnancies with diabetes had higher rates of adverse outcomes including cesarean delivery (GDM 29.4% vs. pregestational 60.0% vs. no diabetes 17.0%, P < 0.001), preeclampsia (GDM 15.7% vs. pregestational 40.0% vs. no diabetes 7.3%, P < 0.001), large-for-gestational-age neonates (GDM 13.7% vs. pre-existing 50.0% vs. no diabetes 5.8%, P < 0.001), and neonatal hypoglycemia (GDM 42.6% vs. pregestational 60.0% vs. no diabetes 13.3%, P < 0.001). Conclusions: The prevalence of pregestational diabetes in our teenage and emerging adult population is similar to that of the general pregnancy population; however, the prevalence of GDM is significantly lower. Overall, diabetes in teenage pregnancy is associated with an elevated risk of adverse maternal and neonatal outcomes. Future research should evaluate interventions aimed at reducing adverse pregnancy outcomes in this vulnerable population.

In this study, we propose two new mathematical models able to quantify glucagon secretion during a graded glucose infusion, in the presence and absence of amino acids. The models provide an index of α-cell responsivity, G 50 , i.e., the glucose increase required to suppress glucose secretion rate (GSR) by 50%. Results show that the presence of amino acids reduced α-cell responsivity to glucose.

ImportanceUnderstanding the interplay between diabetes risk factors and diabetes development is important to develop individual, practice, and population-level prevention strategies.ObjectiveTo evaluate the progression from normal and impaired fasting glucose levels to diabetes among adults.Design, Setting, and ParticipantsThis retrospective community-based cohort study used data from the Rochester Epidemiology Project, in Olmsted County, Minnesota, on 44 992 individuals with at least 2 fasting plasma glucose (FPG) measurements from January 1, 2005, to December 31, 2017. People who met criteria for diabetes on or before their first FPG measurement were excluded. Data were electronically retrieved in December 2019 with analyses finalized in November 2024.ExposuresThe exposure was baseline FPG level, with covariates including the following measures that are consistently recorded in the electronic health record: body mass index (BMI), age, and sex.Main Outcomes and MeasuresThe cumulative probability of freedom from diabetes was estimated and presented graphically using a Kaplan-Meier curve. Multivariable Cox proportional hazards regression modeling was used to estimate the partial hazard ratios (HRs) for variables of interest. Diabetes was defined as an FPG level greater than 125 mg/dL.ResultsA total of 44 992 individuals (mean [SD] age at baseline, 43.7 [11.8] years; 26 025 women [57.8%]) were included. The baseline mean (SD) BMI was 28.9 (6.6). Over a median follow-up of 6.8 years (IQR, 3.6-9.7 years), 3879 individuals (8.6%) developed diabetes. The Kaplan-Meier 10-year cumulative risk of incident diabetes was 12.8% (95% CI, 12.4%-13.2%). All initial FPG levels outside a range of 80 to 94 mg/dL were associated with increased risk for diabetes (ie, FPG &amp;lt;70 mg/dL: HR, 3.49 [95% CI, 2.19-5.57]; FPG 120-125 mg/dL: HR, 12.47 [10.84-14.34]). Other independent risk factors were male sex (HR, 1.31 [95% CI, 1.22-1.40]), older age (≥60 years: HR, 1.97 [95% CI, 1.71-2.28]), and any abnormal category of BMI, including underweight (BMI &amp;lt;18.5: HR, 2.42 [95% CI, 1.77-3.29]; BMI ≥40: HR, 4.03 [95% CI, 3.56-4.56]). There was a significant additive association of variables, particularly FPG level and BMI. For instance, a woman aged 55 to 59 years with a BMI of 18.5 to 24.9 and an FPG level of 95 to 99 mg/dL had an estimated 10-year diabetes risk of 7.0%. However, an almost doubling of risk to 13.0% was observed if the BMI was 30.0 to 34.9, and risk more than doubled again to 28.0% if FPG level also increased to 105 to 109 mg/dL. A nomogram was generated to facilitate individual classification into one of four 10-year risk categories.Conclusions and RelevanceThis retrospective cohort study of 44 992 individuals suggests that FPG level, age, BMI, and male sex were all associated with development of diabetes, with significant interaction between these variables. These data contribute to understanding the clinical course of diabetes and highlight the substantial individual variation in diabetes risk according to commonly measured clinical variables. The findings facilitate lifestyle and pharmacologic interventions to treat those at highest risk of diabetes to reduce future morbidity and mortality. Further work is needed to validate this risk categorization tool for different populations.

Abstract Context Defects in insulin secretion and action contribute to the progression of prediabetes to diabetes. However, the contribution of α-cell dysfunction to this process has been unclear. Objective This work aimed to understand the relative contributions of α-cell and β-cell dysfunction to declining glucose tolerance. Methods A longitudinal, community-based observational study was conducted at a clinical research unit at an academic medical center. We studied 96 individuals without diabetes (age 55 ± 1 years; body mass index 27.7 ± 0.4) on 2 occasions, 3 years apart using an oral 75-g glucose challenge. Indices for insulin secretion and action were estimated using the oral minimal model. Glucagon secretion rate (GSR) was estimated by deconvolution from peripheral glucagon concentrations. Main outcome measures included glucose tolerance status (categorical variable) and then symmetrical percentage change in peak and 120-minute glucose (post oral glucose tolerance test) concentrations (continuous variables). Results A total of 32 individuals progressed from normal to impaired glucose tolerance (IGT) or from IGT to type 2 diabetes. The disposition index (DI) declined in the progressors (568 ± 98 vs 403 ± 65 10−4 dL/kg/min per μU/mL, baseline vs 3 years; P = .04). α-Cell suppression by glucose (δGSR/δglucose) did not change in the nonprogressors (1.5 ± 0.1 vs 1.3 ± 0.1 nmol/min/L; P = .37) but decreased (1.0 ± 0.2 vs 0.8 ± 0.2 nmol/min/L; P &lt; .01) in those who progressed. Analysis of the entire cohort showed that DI and δGSR/δglucose were independently and inversely correlated with an increase in glycemic excursion. Conclusion These data show that α-cell dysfunction accompanies a decline in β-cell function as IGT or overt type 2 diabetes develops.

We describe a method that lowers the limit of quantification of a glucagon immunoassay thereby enhancing the ability to differentiate between normal and abnormal α-cell responsiveness to glucagon.

Abstract Disclosure: J. Hewlett: None. S. Mohan: None. C.J. Davidge-Pitts: None. J. Abeykoon: None. R. Go: None. D.Z. Erickson: None. Objective: Erdheim-Chester Disease (ECD) is a multisystem histiocytic disorder which can infiltrate the pituitary gland, often leading to endocrine dysfunction. Central Arginine Vasopressin Deficiency (cAVP-D) commonly affects ECD patients, and those harboring BRAFV600E are reported to have an increased risk. Insufficient data exist about the risk associated with other mutations, and if cAVP-D or pituitary imaging improves with targeted therapies (TT). Methods: We conducted a review of a prospectively maintained database of adults with ECD treated at a tertiary center between 1992-2023. Objectives of this study were to identify mutations associated with cAVP-D and assess for improvement in cAVP-D (remission of disease or decrease in dose of desmopressin) or pituitary gland involvement (via MRI imaging) following TT for ECD. Results: Of 148 patients with ECD, the majority were male (98, 66.2%) and the mean age at diagnosis was 56.5 years [range: 19-82]. Median length of follow-up was 24 months (95% CI, 17 to 27). Of 121 (81.8%) patients with molecular testing results, 89 (73.6%) harbored a somatic mutation. 67 of 89 (75.3%) carried BRAF mutations, with BRAFV600E in 61 (91.0%) and missense mutations/fusions in 6 (9.0%). 22 of 89 (24.7%) patients harbored other somatic mutations, with MAP2K1 in 13 (14.6%) being the most common. 35 (23.6%) patients were diagnosed with cAVP-D, and the median onset of polyuria and polydipsia prior to diagnosis of ECD was 51 months (95% CI, -120 to -6). Molecular testing was performed in 28 patients with cAVP-D: 17 (60.7%) harbored BRAF mutation and 3 (10.7%) MAP2K1 mutation. There was no significant association between the presence of cAVP-D and MAP2K1 (p=0.69, 95% CI, -0.08 to 0.21). The association between cAVP-D and BRAF did not reach statistical significance (p=0.07, 95%CI, -0.03 to 0.38). Additionally, there was no association between BRAF and timing of cAVP-D symptoms before ECD diagnosis (p=0.08, 95% CI -163.4 to 10.3). Pituitary MRI was available in 32 patients with cAVP-D (91.4%) showing infundibular involvement in 17 (53.1%) and loss of the posterior bright spot in 5 (15.6%). 28 (80%) patients with cAVP-D received systemic therapy, 18 (64.3%) of whom received TT. One patient with cAVP-D was able to discontinue desmopressin. Improvement of pituitary MRI was noted in 7 (21.9%), among whom 4 received TT, 2 received systemic non-TT, and 1 was lost to follow-up. There was no significant MRI improvement associated with TT (p=0.67, 95% CI -0.30 to 0.42). Conclusion: In this large cohort of patients with ECD, of whom the majority underwent molecular testing, we identified no association between MAP2K1 mutation and cAVP-D, and no impact of TT on the clinical course or MRI findings associated with cAVP-D. BRAF mutation carriers were more likely to have cAVP-D and more likely to have onset of symptoms closer to ECD diagnosis, but the results did not reach statistical significance. Presentation: 6/2/2024

Abstract Disclosure: S. Mohan: None. O.A. Shariq: None. J.C. Andrews: None. W.F. Young: None. Background: Adrenal vein sampling (AVS) is performed in patients with primary aldosteronism (PA) to subtype surgically curable unilateral disease. During AVS, iodinated contrast is used to confirm catheterization of adrenal veins for accurate sampling. However, in patients with severe contrast allergy, the optimal method of safely and effectively confirming localization is debatable. Premedication with oral corticosteroids has raised concern for suppression of cortisol and confounding of AVS results. We therefore investigated our experience of AVS after corticosteroid premedication in patients with PA and iodine contrast allergy. Methods: Patients with PA who underwent AVS at our center under continuous cosyntropin infusion (50 mcg/hr started 30 minutes before sampling) between September 1990 - October 2023 were identified. Individuals with documented allergy to iodinated contrast who received corticosteroid premedication were matched 1:1 for age and sex with control patients without contrast allergy or premedication. Baseline demographics, biochemical variables, AVS results, and follow-up data were compared between groups. Results: 1273 AVS studies were performed in 1255 patients with PA and 35 (2.8%) patients received corticosteroid premedication for contrast allergy. Methylprednisolone was used in 32 (91.4%) patients while dexamethasone was used in the rest. No patients experienced a severe breakthrough allergic reaction. Mean age was similar in cases vs. controls (53.9 vs. 54.1 years, P=0.92) with 16 females (45.7%) per group. There were no significant differences in baseline aldosterone-to-renin ratios (57.7 vs. 49.3, P=0.57) or daily defined doses of antihypertensives (5.5 vs. 4.4, P=0.21) between the two groups. Absolute cortisol levels (mcg/dL) from both adrenal veins (AV) and the inferior vena cava (IVC) were similar between cases and controls (right AV: 752.5 vs. 813.7, P=0.48; left AV: 527.2 vs. 462.7, P=0.33; IVC: 23.1 vs. 24.5, P=0.18). The ratio of cortisol in the corresponding AV to the IVC (selectivity index) was &gt;5 in all patients, confirming appropriate cannulation, with similar mean selectivity indices between groups (right AV: 33.0 vs. 33.7, P=0.86; left AV: 22.8 vs. 19.0 P=0.17). Unilateral disease (indicated by a lateralization index &gt;4) was present in 20 (57.1%) patients who received premedication compared with 16 (45.7%) controls (P=0.34). Surgery for unilateral disease was performed in 16 cases and 12 controls, with similar post-op day 1 aldosterone levels in both groups (3.8 vs. 3.3, P=0.36), consistent with surgical cure. Conclusion: In patients with PA and iodine contrast allergy, premedication with corticosteroids prior to cosyntropin-stimulated AVS does not significantly suppress cortisol levels or affect interpretation of AVS results, with comparable rates of disease subtyping and surgical outcomes when compared to a control group. Presentation: 6/3/2024

Abstract Context Multiple common genetic variants have been associated with type 2 diabetes, but the mechanism by which they predispose to diabetes is incompletely understood. One such example is variation in MTNR1B, which implicates melatonin and its receptor in the pathogenesis of type 2 diabetes. Objective To characterize the effect of diabetes-associated genetic variation at rs10830963 in the MTNR1B locus on islet function in people without type 2 diabetes. Design The association of genetic variation at rs10830963 with glucose, insulin, C-peptide, glucagon, and indices of insulin secretion and action were tested in a cohort of 294 individuals who had previously undergone an oral glucose tolerance test (OGTT). Insulin sensitivity, β-cell responsivity to glucose, and Disposition Indices were measured using the oral minimal model. Setting The Clinical Research and Translation Unit at Mayo Clinic, Rochester, MN. Participants Two cohorts were utilized for this analysis: 1 cohort was recruited on the basis of prior participation in a population-based study in Olmsted County. The other cohort was recruited on the basis of TCF7L2 genotype at rs7903146 from the Mayo Biobank. Intervention Two-hour, 7-sample OGTT. Main Outcome Measures Fasting, nadir, and integrated glucagon concentrations. Results One or 2 copies of the G-allele at rs10830963 were associated with increased postchallenge glucose and glucagon concentrations compared to subjects with the CC genotype. Conclusion The effects of rs10830963 on glucose homeostasis and predisposition to type 2 diabetes are likely to be partially mediated through changes in α-cell function.

Abstract Elevated 1,25-dihydroxyvitamin D (1,25(OH)2D) is a rare cause of non–parathyroid hormone (PTH)–mediated hypercalcemia seen in granulomatous disease, malignancy (most often lymphoma), or genetic mutations. Therapeutic options are limited. We report the case of a 67-year-old White man with nonmalignant, nongranulomatous, 1,25(OH)2D-mediated hypercalcemia treated successfully with cinacalcet. At presentation, he had hypercalcemia, hypercalciuria with recurrent nephrolithiasis, low PTH, elevated 1,25(OH)2D, and normal 25-hydroxyvitamin D. The 1,25(OH)2D levels were inappropriate in the setting of hypercalcemia with low PTH. Evaluations for sarcoidosis, tuberculosis, and malignancy were negative. Genetic testing showed biallelic variants in the CYP24A1 gene. Cinacalcet was trialed and showed normalization of calcium levels. On cinacalcet, biochemical indices showed a slight increase in 1,25(OH)2D and 24-hour urine calcium and mild decrease in PTH. He briefly experienced symptomatic hypocalcemia that resolved after reducing cinacalcet dose. Due to limited symptomatic benefit, he opted to stop cinacalcet. Additional follow-up showed intermittently elevated serum calcium levels after stopping cinacalcet, most recently 10.3 mg/dL. Cinacalcet may be a therapeutic option in nonmalignant, 1,25(OH)2D-mediated hypercalcemia. Further study is necessary to confirm efficacy, understand risks and benefits, and elucidate mechanism(s) of action.