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In this study, we propose a new mathematical model able to quantify C-peptide secretion and β-cell responsivity in response to a glucagon bolus in individuals without and with type 2 diabetes. We show that individuals with type 2 diabetes exhibit reduced β-cell responsivity to glucagon.

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 <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 <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 < .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.

Introduction: Living in an area with high Area Deprivation Index (ADI) is linked to worse cardiovascular disease (CVD) outcomes. However, the association of ADI with type 2 diabetes (T2D), a major CVD risk factor, is incompletely described. This knowledge may guide primary CVD prevention. Method: Rochester Epidemiology Project is a medical record linkage system of persons in southeast Minnesota and southwest Wisconsin. We identified 253,890 persons (aged 4–98 yrs on July 1, 2015) in 9 counties with >90% population coverage. ADI scores, from 2015 home addresses, were grouped into quartiles of low (Q1) to high (Q4) deprivation. We excluded persons with type 1 diabetes (T1D) or history of T2D and identified new T2D cases (2015-2020) using ICD codes, HbA1c and medications. We examined the association between ADI quartile and risk of incident T2D using Cox regression with persons right censored at death, T2D, T1D or last visit. Models were adjusted for age and gender, and reported adjusted hazard ratios (aHR [95% confidence interval]). Results: Age, gender, and race statistically differed across ADI quartiles (Table). Age × ADI interaction was significant ( P <.001). T2D incidence ranged from 6.3 (Q1) to 9.0 (Q4) per 1000 person-years ( P <.001). Women vs. men/non-binary persons (combined due to limited non-binary persons) had 30% lower risk of incident T2D (aHR 0.70 [0.67–0.72]). Risk of incident T2D was higher in persons from higher ADI areas. At median age of 48.6 yrs, the risk was 30% higher in Q2 (aHR 1.3 [1.22–1.38]), 38% higher in Q3 (aHR 1.38 [1.30–1.47]) and 53% higher in Q4 (aHR 1.53 [1.43–1.62]) vs. Q1. Higher ADI was associated with higher incident T2D in younger persons, with risk attenuation with increasing age (Figure). Conclusion: In this population cohort, persons, particularly of younger age, living in more deprived areas had a higher risk of incident T2D. ADI may help identify areas for targeted T2D screening, with implications for CVD screening and prevention.

Abstract Introduction Vulnerable populations experience a higher burden of cardiovascular disease.(1) However, the incidence of cardiovascular risk factors, such as diabetes, within these populations, is incompletely characterized. Recently, the United States Centers for Disease Control and Prevention (US CDC) developed the Social Vulnerability Index (SVI) to categorize counties that may be vulnerable to worse health outcomes. The SVI is composed of 4 themes: socioeconomic status (Theme 1), household composition & disability (Theme 2), minority status & language (Theme 3), and housing type & transportation (Theme 4).(2) We sought to evaluate the association of the 4 SVI themes with county incidence of diagnosed diabetes. Method We used CDC data (2004-2019; reported for 94% of US counties), on county incidence of diagnosed diabetes. The SVI themes were scored from 0 to 1 (low to high vulnerability) based on national percentile ranking. We used weighted least squares regression with restricted cubic splines to model the relationship between SVI themes and incidence of diagnosed diabetes (median data 2004−2019), adjusting for median age, sex ratio, state, percent uninsured, food environment index, healthcare providers, and rurality.(3) The partial effects of SVI themes and diabetes incidence were reported as F-statistics (P-values) and diabetes incidence rate ratios (IRR [95% confidence interval]), which were plotted for all values compared with the 50th percentile (SVI 0.5). For each theme, we also present the IRR for a 0.5-point increase when moving over the lower (SVI score 0.5 vs. 0.0) and the upper (1.0 vs. 0.5) half of the SVI score distribution. Results The 4 SVI theme rank scores were significantly associated with diabetes incidence (all, P&lt;.001). However, Theme 1 and 2 scores showed stronger associations with IRR than Theme 3 and 4 (Figure). For Theme 1, SVI score 0.5 vs. 0.0 was associated with a 15% higher incidence (IRR 1.15 [1.13–1.18]) and score 1.0 vs. 0.5 was associated with a 13% higher incidence (IRR 1.13 [1.11–1.16]). For Theme 2, SVI score 0.5 vs. 0.0 was associated with a 16% higher incidence (IRR 1.16 [1.14–1.18]), but there was no difference between rates for SVI score 1.0 vs. 0.5 (IRR 1.01 [0.99–1.03]). For Theme 3, there was no difference between SVI score 0.5 vs. 0.0 (IRR 0.98 [0.96–1.00]), but rates were 8% lower for SVI score 1.0 vs. 0.5 (IRR 0.92 [0.90–0.94]). For Theme 4, SVI score 0.5 vs. 0.0 was associated with a 3% lower incidence (IRR 0.97 [0.96–0.99]) and score 1.0 vs. 0.5 was associated with a 2% higher incidence (IRR 1.02 [1.01–1.04]). Conclusion In US counties, the strength and directionality of the association between SVI themes and diabetes incidence differed by theme and level of SVI scores. These themes, particularly socioeconomic status and household composition & disability may be leveraged to identify high-risk counties for primary prevention of diabetes, with implications for reduction in cardiovascular risk.

Abstract Disclosure: M. Moazzami: None. N. Venkatesan: None. K.S. Rajagopalan: None. A.V. Vella: None. A. Egan: None. Gestational diabetes mellitus (GDM) affects approximately 10% of pregnancies, with rates almost doubling in minority subgroups. Higher body mass index (BMI) is a significant GDM risk factor, and BMI ≥ 25kg/m2 is often used as a criterion in risk factor-based screening programs. However, up to 60% of individuals with GDM have a normal BMI, and it is unclear if this offers protection against associated adverse outcomes. Furthermore, many prior studies fail to address the fact that those of Asian descent require a lower BMI cut-off, given their different distribution of body fat. Our study evaluated GDM pregnancy outcomes using BMI as a risk indicator. We compared individuals with BMIs &lt; 25 kg/m2, 25-30 kg/m2, and &gt; 30 kg/m2. For individuals that self-identified as Asian, we adjusted BMI categories: &lt;23 kg/m2 for normal weight, 23-30 kg/m2 for overweight, and &gt;30 kg/m2 for obese. We identified 2212 subjects diagnosed with GDM via universal screening and Carpenter and Coustan criteria at our institution from 2018 - 22. In total, 508 (23.0%) were normal weight, 611 (27.6%) overweight, and 1093 (49.4%) obese. The average maternal age was 31 years. Higher proportions identified as Hispanic and non-White race in overweight and obese categories. Maternal adverse outcomes were higher in obese compared to overweight or normal BMI categories (cesarian delivery: normal 26.7 v overweight 28.3 v obese 22.7%, p&lt;0.001; hypertensive disorders: normal 13.2 v overweight 12.5 v obese 22.7%, p &lt;0.001). Pharmacological therapy was required in 50% with obesity versus 24.8% in normal, and 28.7% in overweight categories (p&lt;0.001). While there were no differences in live birth rates across categories, infants born to mothers with obesity had a higher birthweight (normal 3.30 v overweight 3.38 v obese 3.45kg, p&lt;0.001) and were more likely to have neonatal hypoglycemia (normal 28.7 v overweight 25.5 v obese 43.8%, p&lt;0.001) and require intensive care unit admission (normal 8.4 v overweight 5.5 v obese 12.7%, p&lt;0.001). Attendance at postpartum glucose testing varied across BMI categories with lower attendance in mothers with obesity followed by normal weight BMI (normal 40.75 v overweight 45.99 v obese 36.2%, p&lt;0.001). Compared to overweight individuals, those with normal weight exhibited higher rates of postpartum glucose intolerance (12.4 v 6.9%, p =0.002). However, those with obesity had the highest rates of glucose intolerance (20.7%, p&lt;0.0002). Individuals with normal weight had the highest rates of breastfeeding (normal 95.9 v overweight 92.8 v obese 91.4% p=0.006). This study highlights the nuanced relationship between BMI and pregnancy outcomes in GDM. While maternal obesity was associated with the poorest outcomes, those with normal BMI were not protected compared to overweight individuals, and experience higher rates of postpartum glucose intolerance. Presentation: 6/2/2024

Abstract Disclosure: R. Kennedy: None. D.A. D'Alessio: None. A.V. Vella: None. Introduction: Selective arterial calcium stimulation testing (SACST) can be utilized in patients to localize solitary insulinomas when imaging is non diagnostic. While a heterogenous stimulation pattern suggests NIPHS, or multiple insulinomas this case uniquely demonstrates such a pattern with a solitary insulinoma. Clinical Case: The patient is a 48 year old female who presented to the emergency department (ED) for bizarre behavior which resolved with a sweetened drink. Serum glucose was 62 mg/dL, she was treated with IV dextrose and was discharged from the ED. She was referred to outpatient endocrinology for further evaluation where continuous glucose monitoring confirmed predominantly fasting hypoglycemia. Adrenal insufficiency was excluded. She was admitted for a 72 hour inpatient fast where the patient achieved hypoglycemia within 24 hours, with glucose 46 mg/dL (associated with neuroglycopenic symptoms), beta hydroxybutyrate &lt; 0.18 mmol/L, insulin 3.9 mcIU/mL, proinsulin 157pmol/L, c-peptide 1.4 ng/mL and a glucose rise greater than 25mg/dL after glucagon administration. Sulfonylurea screen and insulin antibodies were negative; IGF1 within normal limits. These labs were consistent with hyperinsulinemic hypoglycemia. An MRI pancreas however did not reveal an insulinoma. The patient therefore underwent a SACST, demonstrating a 10 fold response in the territory of the gastroduodenal artery and splenic artery, as well as a 3 fold response in the superior mesenteric artery. This heterogenous pattern in addition to the marked response in each arterial territory raised the possibility of multiple insulinomas. However as there were no tumors present on imaging, medical management was initiated with close follow up. She was trialed with months of somatostatin analogs and diazoxide with minimal improvement in the frequency and severity of her hypoglycemia. About a year after her initial diagnosis, repeat abdominal imaging (CT and MRI) revealed an 8 mm arterial hyper-enhancing lesion in the body of the pancreas concerning for neuroendocrine tumor. Repeat SACST was performed, this time showing a greater than 10 fold response in all three arterial territories. Angiography showed a tumor blush that was visible when each of the three major arteries were injected sequentially. She underwent laparoscopic pancreatic enucleation. The lesion was located on the body of the pancreas, with histology confirming an insulinoma. The patient responded promptly post operatively; her symptoms resolved without further need of medical management. Conclusion: Our case shows that the interpretation of an SACST should take into account the arterial anatomy before ascribing a non-focal response to multiple territories of insulin hypersecretion. Presentation: 6/1/2024

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.

The T allele at rs7903146 in TCF7L2 increases the rate of conversion from prediabetes to type 2 diabetes. This has been associated with impaired β-cell function and with defective suppression of α-cell secretion by glucose. However, the temporal relationship of these abnormalities is uncertain. To study the longitudinal changes in islet function, we recruited 128 subjects, with 67 homozygous for the diabetes-associated allele (TT) at rs7903146 and 61 homozygous for the protective allele. Subjects were studied on two occasions, 3 years apart, using an oral 75-g glucose challenge. The oral minimal model was used to quantitate β-cell function; the glucagon secretion rate was estimated from deconvolution of glucagon concentrations. Glucose tolerance worsened in subjects with the TT genotype. This was accompanied by impaired postchallenge glucagon suppression but appropriate β-cell responsivity to rising glucose concentrations. These data suggest that α-cell abnormalities associated with the TT genotype (rs7903146) occur early and may precede β-cell dysfunction in people as they develop glucose intolerance and type 2 diabetes. Article Highlights