Insulin Assay Research Articles

Nuclear Magnetic Resonance Derived Biomarkers for Evaluating Cardiometabolic Risk in Youth and Young Adults Across the Spectrum of Glucose Tolerance.

Youth with obesity have an increased risk for cardiometabolic disease, but identifying those at highest risk remains a challenge. Four biomarkers that might serve this purpose are “by products” of clinical NMR LipoProfile® lipid testing: LPIR (Lipoprotein Insulin Resistance Index), GlycA (inflammation marker), BCAA (total branched-chain amino acids), and glycine. All are strongly related to insulin resistance and type 2 diabetes (T2DM) in adults (glycine inversely) and are independent of biological and methodological variations in insulin assays. However, their clinical utility in youth is unclear. We compared fasting levels of these biomarkers in 186 youth (42 lean normal glucose tolerant (NGT), 88 obese NGT, 23 with prediabetes (PreDM), and 33 with T2DM. All four biomarkers were associated with obesity and glycemia in youth. LPIR and GlycA were highest in youth with PreDM and T2DM, whereas glycine was lowest in youth with T2DM. While all four were correlated with HOMA-IR (Homeostatic Model Assessment for Insulin Resistance), LPIR had the strongest correlation (LPIR: r = 0.6; GlycA: r = 0.4, glycine: r = −0.4, BCAA: r = 0.2, all P < 0.01). All four markers correlated with HbA1c (LPIR, GlycA, BCAA: r ≥ 0.3 and glycine: r = −0.3, all P < 0.001). In multi-variable regression models, LPIR, GlycA, and glycine were independently associated with HOMA-IR (Adjusted R2 = 0.473, P < 0.001) and LPIR, glycine, and BCAA were independently associated with HbA1c (Adjusted R2 = 0.33, P < 0.001). An LPIR index of >44 was associated with elevated blood pressure, BMI, and dyslipidemia. Plasma NMR-derived markers were related to adverse markers of cardiometabolic risk in youth. LPIR, either alone or in combination with GlycA, should be explored as a non-insulin dependent predictive tool for development of insulin resistance and diabetes in youth.Clinical Trial Registration Clinicaltrials.gov, identifier NCT:02960659

Waist-to-height ratio and metabolic phenotype compared to the Matsuda index for the prediction of insulin resistance

Current screening algorithms for type 2 diabetes (T2D) rely on fasting plasma glucose (FPG) and/or HbA1c. This fails to identify a sizeable subgroup of individuals in early stages of metabolic dysregulation who are at high risk for developing diabetes or cardiovascular disease. The Matsuda index, a combination of parameters derived from a fasting and postprandial insulin assay, is an early biomarker for metabolic dysregulation (i.e. insulin resistance/compensatory hyperinsulinemia). The aim of this analysis was to compare four widely available anthropometric and biochemical markers indicative of this condition [waist-to-height ratio (WHtR), hypertriglyceridemic-waist phenotype (HTW), triglycerides-to-HDL-C ratio (TG/HDL-C) and FPG] to the Matsuda index. This cross-sectional analysis included 2231 individuals with normal fasting glucose (NFG, n = 1333), impaired fasting glucose (IFG, n = 599) and T2D (n = 299) from an outpatient diabetes clinic in Germany and thus extended a prior analysis from our group done on the first two subgroups. We analyzed correlations of the Matsuda index with WHtR, HTW, TG/HDL-C and FPG and their predictive accuracies by correlation and logistic regression analyses and receiver operating characteristics. In the entire group and in NFG, IFG and T2D, the best associations were observed between the Matsuda index and the WHtR (r = − 0.458), followed by HTW phenotype (r = − 0.438). As for prediction accuracy, WHtR was superior to HTW, TG/HDL-C and FPG in the entire group (AUC 0.801) and NFG, IFG and T2D. A multivariable risk score for the prediction of insulin resistance was tested and demonstrated an area under the ROC curve of 0.765 for WHtR and its interaction with sex as predictor controlled by age and sex. The predictive power increased to 0.845 when FPG and TG/HDL-C were included. Using as a comparator the Matsuda index, WHtR, compared to HTW, TG/HDL-C and FPG, showed the best predictive value for detecting metabolic dysregulation. We conclude that WHtR, a widely available anthropometric index, could refine phenotypic screening for insulin resistance/hyperinsulinemia. This may ameliorate early identification of individuals who are candidates for appropriate therapeutic interventions aimed at addressing the twin epidemic of metabolic and cardiovascular disease in settings where more extended testing such as insulin assays are not feasible.

Biological Pathways in Adolescent Aortic Stiffness.

BackgroundAortic stiffening begins in youth and antedates future hypertension. In adults, excess weight, systemic inflammation, dyslipidemia, insulin resistance, neurohormonal activation, and altered adipokines are implicated in the pathogenesis of increased aortic stiffness. In adolescents, we assessed the relations of comprehensive measures of aortic stiffness with body mass index (BMI) and related but distinct circulating biomarkers.Methods and ResultsA convenience sample of 246 adolescents (mean age, 16±2 years; 45% female, 24% Black, and 43% Hispanic) attending primary care or preventive cardiology clinics at 2 tertiary hospitals was grouped as normal weight (N=98) or excess weight (N=148, defined as BMI ≥age‐ and sex‐referenced 85th percentile). After an overnight fast, participants underwent anthropometry, noninvasive arterial tonometry, and assays for serum lipids, CRP (C‐reactive protein), glucose, insulin, renin, aldosterone, and leptin. We used multivariable linear regression to relate arterial stiffness markers (including carotid‐femoral pulse wave velocity) to BMI z score and a biomarker panel. Carotid‐femoral pulse wave velocity was higher in excess weight compared with normal weight group (5.0±0.7 versus 4.6±0.6 m/s; P<0.01). After multivariable adjustment, carotid‐femoral pulse wave velocity was associated with BMI z score (0.09 [95% CI, 0.01–0.18]; P=0.04) and with low‐density lipoprotein cholesterol (0.26 [95% CI, 0.03–0.50]; P=0.03).ConclusionsHigher BMI and low‐density lipoprotein cholesterol were associated with greater aortic stiffness in adolescents. Maintaining optimal BMI and lipid levels may mitigate aortic stiffness.

The mechanism of leptin and IGF-1 in the diabetic rheumatoid arthritis Iraqi patients

We aimed here to study the impact of leptin on insulin like growth factor-1 (IGF-1) level to imply its antidiabetic effect on Iraqi rheumatoid arthritis’s, who was with and without diabetes mellitus.Rheumatoid arthritis is a chronic inflammatory disease, primarily targets the synovium and articular cartilage, which causes joint damage. Although the role of adipocytokines in mediating damages of joint has recently suggested, it is still a matter of considerable debate.METHODS: Patients diagnosed as diabetic rheumatoid arthritis aged from 33-60 years and others diagnosed as non-diabetic rheumatoid arthritis were compared with healthy control (aged 33-46 years). Some biochemical parameters have determined, such as fasting serum glucose, glycated hemoglobin, lipid profile, serum fasting insulin, IGF-1, and leptin, using ELISA and immune radiometric assay. Results indicated an elevation in some biochemical parameters in diabetic rheumatoid arthritis’s when compared with patients without diabetes. There was a significant increase in fasting serum glucose and some of the lipid components in diabetic rheumatoid arthritis patients compared to that non-diabetic. A significant elevation of leptin in diabetic rheumatoid arthritis patients compared to control (p<0.003). However, a non-significant difference of leptin was detected between diabetic rheumatoid arthritis and non-diabetic patients. In addition, some other parameters were significantly reduced in diabetic rheumatoid arthritis patients when compared to non-diabetic patients, such as high-density lipoprotein and IGF-1. This study highlights that leptin could act as pro-inflammatory mediator in rheumatoid arthritis. The negative correlation between leptin level and IGF-1 plays an important role in understanding the metabolic pathogenesis of rheumatoid arthritis.

A Sensitive Plasma Insulin Immunoassay to Establish the Diagnosis of Congenital Hyperinsulinism.

BackgroundThe diagnosis of congenital hyperinsulinism (CHI) may be hampered by a plasma (p-) insulin detection limit of 12–18 pmol/L (2–3 mU/L).ObjectiveTo evaluate the diagnostic performance of a sensitive insulin immunoassay and to find the optimal p-insulin cut-off for the diagnosis of CHI.MethodsDiagnostic fasting tests, performed without medication or i.v.-glucose, were investigated in children with a clinical diagnosis of CHI, or idiopathic ketotic hypoglycemia (IKH). The CHI diagnosis was either clinical or by the alternative, p-insulin-free criteria; hypoglycemia plus disease-causing genetic mutations and/or CHI-compatible pancreatic histopathology. We included diagnostic p-insulin samples with simultaneous p-glucose <3.2 mmol/L and used a sensitive insulin assay (Cobas e411 immunoassay analyzer; lower detection limit 1.2 pmol/L; normal range 15.1–147.1 pmol/L). Receiver operating characteristics area under the curve (ROC AUC) values and optimal cut-offs were analyzed for the performance of p-insulin to diagnose CHI.ResultsIn 61 CHI patients, the median (range) p-insulin was 76.5 (17–644) pmol/L compared to 1.5 (1.5–7.7) pmol/L in IKH patients (n=15). The ROC AUC was 1.0 for the diagnosis of CHI defined both by the clinical diagnosis (n=61) and by alternative criteria (n=57). The optimal p-insulin cut-offs were 12.3 pmol/L, and 10.6 pmol/L, at p-glucose <3.2 mmol/L (n=61), and <3.0 mmol/L (n=49), respectively.ConclusionsThe sensitive insulin assay performed excellent in diagnosing CHI with optimal p-insulin cut-offs at 12.3 pmol/L (2.0 mU/L), and 10.6 pmol/L (1.8 mU/L), at p-glucose <3.2 mmol/L, and <3.0 mmol/L, respectively. A sensitive insulin assay may serve to simplify the diagnosis of CHI.

The Impact of Exogenous Insulin Input on Calculating Hepatic Clearance Parameters.

Model-based metabolic tests require accurate identification of subject-specific parameters from measured assays. Insulin assays are used to identify insulin kinetics parameters, such as general and first-pass hepatic clearances. This study assesses the impact of intravenous insulin boluses on parameter identification precision. Insulin and C-peptide data from two intravenous glucose tolerance test (IVGTT) trials of healthy adults (N = 10 × 2; denoted A and B), with (A) and without (B) insulin modification, were used to identify insulin kinetics parameters using a grid search. Monte Carlo analysis (N = 1000) quantifies variation in simulation error for insulin assay errors of 5%. A region of parameter values around the optimum was identified whose errors are within variation due to assay error. A smaller optimal region indicates more precise practical identifiability. Trial results were compared to assess identifiability and precision. Trial B, without insulin modification, has optimal parameter regions 4.7 times larger on average than Trial A, with 1-U insulin bolus modification. Ranges of optimal parameter values between trials A and B increase from 0.04 to 0.12 min-1 for hepatic clearance and from 0.07 to 0.14 for first-pass clearance on average. Trial B's optimal values frequently lie outside physiological ranges, further indicating lack of distinct identifiability. A small 1-U insulin bolus improves identification of hepatic clearance parameters by providing a smaller region of optimal parameter values. Adding an insulin bolus in metabolic tests can significantly improve identifiability and outcome test precision. Assay errors necessitate insulin modification in clinical tests to ensure identifiability and precision.

Insulin Difference of Boys and Girls at Birth

Different opinions exist whether girls show higher insulin levels than boys at birth. Insulin values of 863 consecutively born babies whose mothers had no screening for gestational diabetes may provide clarification. Cord serum, measured with a commercially available insulin assay, is therefore retrospectively analyzed for insulin differences in boys and girls. Girls show higher insulin values than boys (♀6.0/♂5.2 µU/ml). Insulin-sex-difference amounts to 0.8 µU/ml [95% CI 0.3 to 1.3]; p-value 0.003. It is also found in AGA babies, in children of multiparous women, after elective caesarean section and spontaneous vaginal delivery (0.8/1.2/1.7/0.9 µU/ml; p-values 0.003/0.001/0.025/0.006). Girls of multiparous women with macrosomia (LGA/≥ 4000 g) show the highest values of insulin (13.8/13.8 µU/ml) and of insulin-sex-difference (5.5/5.6 µU/ml, p-value 0.001/0.001). This insulin difference can be seen in firstborn babies weighing less than 3640 g, but ≥ 4060 g an inverse insulin sex difference (-5.4 µU/ml; p-value 0.023) with higher insulin values in boys exists (11.3 µU/ml). Children with hyperinsulinaemia (≥20 µU/ml) (17♀, 11♂) show no insulin difference, girls weigh more than boys (154 g, p-value 0.463) and later born babies more (695 g, p-value 0.0001) than firstborns. Higher insulin values of girls have been confirmed. An as yet unknown inverse insulin difference with higher insulin values of firstborn boys with macrosomia has been proved.

Impact of leptin levels in metabolic syndrome

Background: Metabolic syndrome (MS) is a group of risk factors that raises risk of heart disease, diabetes, stroke, and other health problems. Aim and Objectives: The study aimed to find out correlation between leptin level and MS components. Materials and Methods: This was a randomized cross-sectional study involved 150 MS patient. Fasting blood sugar, glycated hemoglobin, lipid profiles, leptin and insulin assays, and other anthropometrics measures were measured using standard protocols. Results: The results revealed that there was significant correlation between leptin level and body mass index, gender, fasting blood glucose, and glycosylated hemoglobin, P < 0.01. Conclusion: This study was showed that there was significant impact of leptin level on MS.

Insulin-like growth factor-2 regulates basal retinal insulin receptor activity

The retinal insulin receptor (IR) exhibits basal kinase activity equivalent to that of the liver of fed animals, but unlike the liver, does not fluctuate with feeding and fasting; it also declines rapidly after the onset of insulin-deficient diabetes. The ligand(s) that determine basal IR activity in the retina has not been identified. Using a highly sensitive insulin assay, we found that retinal insulin concentrations remain constant in fed versus fasted rats and in diabetic versus control rats; vitreous fluid insulin levels were undetectable. Neutralizing antibodies against insulin-like growth factor 2 (IGF-2), but not insulin-like growth factor 1 (IGF-1) or insulin, decreased IR kinase activity in normal rat retinas, and depletion of IGF-2 from serum specifically reduced IR phosphorylation in retinal cells. Immunoprecipitation studies demonstrated that IGF-2 induced greater phosphorylation of the retinal IR than the IGF-1 receptor. Retinal IGF-2 mRNA content was 10-fold higher in adults than pups and orders of magnitude higher than in liver. Diabetes reduced retinal IGF-2, but not IGF-1 or IR, mRNA levels, and reduced IGF-2 and IGF-1 content in vitreous fluid. Finally, intravitreal administration of IGF-2 (mature and pro-forms) increased retinal IR and Akt kinase activity in diabetic rats. Collectively, these data reveal that IGF-2 is the primary ligand that defines basal retinal IR activity and suggest that reduced ocular IGF-2 may contribute to reduced IR activity in response to diabetes. These findings may have importance for understanding the regulation of metabolic and prosurvival signaling in the retina.

Rapid and Sensitive Analytical Method for the Determination of Insulin in Liposomes by Reversed-Phase HPLC

Insulin is an important anabolic hormone that regulates the metabolism of carbohydrates, lipids and proteins. In this study, a reverse-phase liquid chromatography (RP-LC) method was successfully validated and tested for the encapsulation efficiency assay of insulin and in vitro release studies. HPLC analyses were carried out using a RP C18- Luna® Phenomenex (4.6 × 250 mm, 5 ?m particle size) column maintained at room temperature, using a mobile phase constituted by a mixture of acetonitrile and 0.1% TFA aqueous solution (60:40, v/v), in an isocratic mode with a flow rate of 1.0 mL/ min, with ultraviolet detection at 214 nm and 20 ?L of injection volume. Method validation was performed according recognized guidelines for system suitability, specificity, linearity, precision, accuracy, LOD, LOQ and robustness. The method was shown to be linear in the range of 0.5-100 ?g/mL (r2 = 0.9993) selective, precise, robust, accurate with LOD and LOQ values were 0.097 ?g/mL and 0.294 ?g/mL, respectively. The developed method proved to be adequate to analyze the encapsulation efficiency and the profile of insulin release from liposomes.

Oral Glucose Tolerance Test with Insulin Assay and the evaluation of Insulin Resistance and Impaired Beta-cell function in primary prevention for Type 2 Diabetes

Background: Insulin resistance and impaired beta-cell function are associated with type 2 diabetes mellitus (T2DM). Many insulin resistance and beta-cell function indices have been developed using the data from an oral glucose tolerance test (OGTT) with insulin assay. However, insulin assays are not widely used along with the OGTT in primary prevention outpatient clinics. We aimed to evaluate the association of having impaired fasting glucose (IFG), impaired glucose tolerance (IGT), isolated or combined, with insulin resistance and impaired beta-cell function in subjects at risk for T2DM. Methods: This is a cross-sectional study that included 376 subjects who underwent an OGTT who had at least two risk factors for T2DM without any chronic disease. Results: Participants were 51.6±8.2 years old, 71.8% were women, had a mean body mass index (BMI) of 30.1±6.5 kg/m2, 42.4% had obesity and 26.7% hypertension. A HOMA-IR ≥2.5 was independently associated with male sex, BMI&gt;25kg/m2, and with isolatedIFG, isolated-IGT, or combined (p&lt;0.05 for all). On the other hand, only overweight, but not obesity, was independently associated with impaired beta-cell function (disposition index &lt;1.24). Additionally, combined IFG and IGT had 29.7 higher odds to have impaired beta-cell function compared with those that had a normal OGTT. Conclusions: IFG alone, IGT alone, or the presence of both, are associated with higher odds to have insulin resistance and impaired beta-cell function in asymptomatic subjects at risk for T2DM without any chronic disease. Further studies are needed to evaluate this associations with the risk to develop T2DM, cardiovascular events and mortality.

Development of the embryonic liver and pancreas of the Chinese softshell turtle Trionyx sinensis

ABSTRACT The research on hatching ecology of the Chinese softshell turtle Trionyx sinensis has essential guiding roles to clarify the physiological and ecological mechanism of reptile evolution. The aim of this study is to describe the histological changes, differentiation, and maturation of some functional cells during the genesis and development of the liver and pancreas of the Chinese softshell turtle T. sinensis. Softshell turtle eggs were incubated under artificial conditions and hatched within 41–45 days. Hematoxylin and eosin-stained embryonic pancreas and liver were examined at various time points from 2 to 31 days and compared with that of other reptiles, amphibians, fishes, and birds in the literature. Immunohistochemical assay for glucagon and insulin was performed on paraformaldehyde-fixed embryos to identify functional cells in the pancreas. Pancreatic endocrine cells of T. sinensis have secretory ability at day 26 of embryonic development, and the dispersed pancreatic endocrine cells may be the result of the incomplete pancreatic development.

Preliminary Nutrient Determination and Regeneration of Pancreatic Islet Cells by Extracts of Spondias mombin Leaves in Streptozotocin-Induced Diabetic Rats

Background: There is a growing trend towards the use of medicinal plant that can prevent degeneration of pancreatic cells and regenerate islet cells in diabetes treatment Objectives: The possible effects of the extracts of Spondias mombin leaves on the regeneration of pancreatic beta cells in streptozotocin (STZ)-induced diabetic rats were determined in this study. Methods: Twenty-five male Wistar rats were randomly divided into 5 groups (A-E) including normal and diabetic rats. Aqueous and ethanol extracts of S. mombin were administered orally to diabetic rats in groups D and E for 12 weeks. Blood samples were collected for serum insulin and C-peptide assays. The pancreases were also collected for histopathological examination. Additionally, mineral and vitamin contents of the leaves were determined using standard procedures. Results: The highest vitamin content was vitamin C in the leaves, while the highest mineral content was calcium. Treatment with extracts of Spondias mombin attenuated the STZ-induced hypoinsulinemia, which was evident from the increased serum insulin and c-peptide levels in the extract treated groups. Histopathological examination of the pancreas revealed an increase in the number and size of the pancreatic beta cells in the extracts treated groups in comparison to the shrunken and diminished islet cells observed in the untreated animals. Conclusion: Extracts of S. mombin leaves are capable of regenerating pancreatic β-cells which were destroyed by streptozotocin induction.

Colorimetric detection of insulin in human serum using GO/AuNPs/TX-100 nanocomposite.

In this study, graphene oxide/gold nanoparticles/Triton X-100 nanocomposites (GO/AuNPs/TX-100) were synthesized using the sonochemical method and their ability in ultrasound-assisted colorimetric detection of insulin was investigated. The synthesized GO/AuNPs/TX-100 nanocomposites were characterized by UV-visible absorption spectroscopy and TEM analysis. The interaction between the nanocomposites and insulin was observed by both naked eye and optical absorption spectroscopy. The GO/AuNPs/TX-100 nanocomposites displayed apparent color changes (red to blue) and absorption spectra changes (decreasing of the band around 528nm and appearance of a new red-shifted band at 640nm) in presence of insulin. The interaction mechanism of the nanocomposites and insulin was discussed. It is based on the special structure of insulin, that insulin can be easily self-assemble into the GO/AuNP/TX-100 nanocomposites and can also play the role of a bridge between two different GO/AuNPs/TX-100 nanocomposites by peptide chains. The effective parameters for insulin detection were optimized. The colorimetric method was used for quantification of insulin in the range of 2-300ngmL-1 with a detection limit of 0.1ngmL-1. Moreover, the relative standard deviation of the method was 3.1 and 2.7% (n=10) at concentrations of 50 and 200ngmL-1, respectively on the same day and 4.8% at a concentration (200.0ngmL-1) on five consecutive days. The present method was utilized for insulin assay in human blood serums with satisfactory results.

The Biochemical and Histological Effect of Cadmium Chloride on the Pancreas of Adult Albino Rats and the Possible Protective Effect of Nigella Sativa Seeds

Aim: The current study evaluates the important role of Nigella Sativa against cadmium (Cd) induced toxic changes in pancreasof rats.Materials and Methods: Eighteen adult Wistar albino rats were divided into three equal groups. Control group, cadmiumtreated group that received 5 mg CdCl2/kg BW/day dissolved in water orally for three months, and cadmium with Nigellasativa (NS) group received a mixture of 1g/kg/day of aqueous suspension of Nigella sativa seeds powder and 5 mgCdCl2/kg BW/day dissolved in water for three consecutive months. Hormonal assay of insulin was done. Pancreatic tissueswere prepared for both Hematoxylin and Eosin and toluidine blue. Electron microscopic study of pancreatic tissues was alsodone.Results: The present study showed that the administration of CdCl2 induced evident decrease in insulin serum level. Thebiochemical results were confirmed by histological investigations where degenerative changes of pancreatic acini with lossof normal lobular architecture, distorted pancreatic acini, degenerated and widely separated cells in the islets of Langerhans,blood vessels congestion and aggregation of perivascular cellular infiltrates were detected in pancreatic tissues stained withH&E. Toluidine blue-stained sections showed few deeply stained apical zymogen granules in some acini, whereas other acinishowed absence of these granules.Administration of NS with CdCl2 showed a significant improvement in the measured serum insulin level and histologicalpictures.Conclusion: CdCl2 induced several toxic changes in the exocrine and endocrine parts of pancreas of rats. NS could protect thepancreas against these alterations.

100-OR: High-Affinity Islet Autoantibodies Predict Progression to Diabetes in Those Who Seroconvert after Age 10

The objective of this study was to determine if islet autoantibodies (IA) can develop de novo in youth ≥10 y. We also explored the risk of progression to T1D in youth seroconverting to IA after 10 y. From the prospective DAISY birth cohort (n=2547), we excluded those who were ever previously IA positive, disenrolled prior to age 10, or had &amp;gt;24 month gap in annual IA testing, leaving 917 for analysis. Seroconversion was defined as IA+ by radiobinding assays for insulin, GAD, IA-2 or ZnT8 autoantibodies, confirmed within 3-6 months. The same autoantibodies were also measured by electrochemiluminescence (ECL) assays, to identify high-affinity IA. IA developed after age 10 at a higher rate (p=0.049) in first-degree relatives than in general population youth with increased-risk HLA (Figure 1); there was no difference by sex or race/ethnicity. Of the 35 IA+ seroconverters, 6 progressed to T1D, during a median follow-up of 5.04 years (IQR: 3.56-8.45). This included 2 of 5 individuals who were multiple IA+ at seroconversion, with at least one IA confirmed as high-affinity by ECL. Among those with a single persistent IA+ at seroconversion, 4/9 youth with high-affinity IA (ECL+) progressed to T1D, compared to 0/21 of the youth with low-affinity IA (ECL-). In conclusion, seroconversion continues after age 10. In our genetically at-risk cohort, all who progress to T1D had high-affinity IA confirmed by ECL. Disclosure B.I. Frohnert: None. F. Dong: None. K. Waugh: None. A. Steck: None. J.M. Norris: None. L. Yu: None. M. Rewers: None. Funding JDRF (5-ECR-2017-388-A-N); National Institutes of Health (R01DK32493)

MON-640 Endogenous Insulin and C-Peptide Suppression Test Using a Rapid-Acting Insulin Analog in the Diagnosis of Insulinoma

C-peptide suppression test (CPS) was shown to diagnose the cause of hyperinsulinemic hypoglycemia, i.e. insulinoma, as effectively as supervised 72-hour fast test with less time consuming and cost. In the conventional CPS, regular insulin (RI) is used to induce hypoglycemia that subsequently suppresses endogenous insulin secretion. As RI is measurable in plasma insulin (PI) assay, plasma C-peptide (PCP) but not PI response is therefore used for assessment of endogenous insulin secretion in CPS using RI. As rapid acting insulin analogs (RA) are not measurable in a selected PI assay, both PCP and PI levels can be used to assess endogenous insulin secretion if an RA is used instead of RI in CPS. There is no study on PI and PCP responses to RA in insulinoma. This study aimed to examine efficacy of modified CPS, so-called insulin and C-peptide suppression test (ICPS) by using an RA (insulin aspart) in the diagnosis of insulinoma. Ten patients, 7 with histopathological proven insulinoma (IN) and 3 with non-insulinoma (non-IN), underwent ICPS. Blood samples were collected for measurement of plasma glucose (PG), PCP, and PI using a Roche Cobas 8000 module e602 which does not measure insulin aspart at before and every 10-20 minutes during intravenous infusion of insulin aspart at the rate of 0.05-0.075 unit/kg/hr. The test was terminated if the patients had a PG level of <40 mg/dL. There was no difference in baseline biochemical data between two groups. At the end of the test, IN had significantly higher PCP level (range: 0.60-10.20 vs. 0.31-0.48 ng/mL and median: 4.67 vs. 0.47 ng/mL; p = 0.017), lower percentage of PCP suppression (range: 2.10-53.10% vs. 63.08-91.24% and mean: 24.78 ± 19.4% vs. 73.17 ± 15.7%; p = 0.005), higher PI level (range: 1.13-113.70 vs. 0.22-0.73 µIU/mL and median: 21.29 vs. 0.49 µIU/mL; p = 0.017) and lower percentage of PI suppression (range: -14.63-81.32% vs. 88.14-96.10% and mean: 28.45 ± 36.2% vs. 93.31 ± 4.5%; p = 0.003) than did the non-IN. No overlapping of these parameters was observed between IN and non-IN. Using the same cut-off levels as the supervised 72-hour fast test, the insulin criterion (≥3 µIU/mL) in ICPS had a sensitivity of 86% and a specificity of 100% and the C-peptide criterion (≥0.6 ng/mL) in ICPS had a sensitivity of 100% and a specificity of 100%. There was a high correlation of 89% between using PCP and PI responses. In conclusion, ICPS using an RA is effective in the diagnosis of insulinoma.

SAT-040 Changes in Metabolic Parameters After Administration of Novel Oral Androgens with Progestational Activity for 28 Days

Background: While the metabolic effects of testosterone have been well studied, the effects of co-administration of an androgen and progestin are less established. Two novel compounds being investigated for male hormonal contraception, dimethandrolone undecanoate (DMAU) and 11β-methyl-19-nortestosterone dodecylcarbonate (11β-MNTDC), have both androgenic and progestational activity.Aim: Characterize the effects of DMAU and 11β-MNTDC on metabolic parameters including weight, lipid parameters, insulin resistance, and adiponectin.Methods: Two randomized, double-blind, placebo-controlled studies in healthy men were previously performed to assess the safety and tolerability of DMAU and 11β-MNTDC taken orally for 28 days. Insulin and adiponectin assays were performed on a subset of banked samples. Changes in weight, LDL-C, HDL-C, fasting glucose, HOMA-IR, and adiponectin were assessed. Two way ANOVA with post hoc Tukey HSD was performed to assess for dosage (0, 200, or 400mg) and drug (DMAU or 11β-MNTDC) effects.Results: A total of 85 subjects were included in this secondary analysis. There was a statistically significant decrease in HDL-C (mean change -11 and -15 mg/dL) and increase in weight (3 and 2 kg) and LDL-C (18 and 23 mg/dL) in the DMAU and 11β-MNTDC 400mg groups respectively. There was no significant difference between the 200 and 400 mg groups nor differences between the two androgens. There were no statistically significant changes in fasting glucose, adiponectin or HOMA-IR.Conclusion: There were mild changes in weight, HDL-C, and LDL-C after 28 days of DMAU and 11β-MNTDC without significant changes in markers of insulin resistance or differences between the two compounds. Changes in metabolic parameters should be monitored and considered during further development of compounds for male hormonal contraception.

SAT-624 Predictive Ability of Lipoprotein Insulin Resistance (LPIR) Score in South Asians: A Comparison of Surrogate Indices of Insulin Sensitivity/Resistance

South Asians (SA) are at higher risk for developing insulin resistance (IR) and type 2 diabetes. Consequently, identifying IR in this population is important. Lack of standardization and harmonization of insulin assays limit the clinical use of insulin-based surrogate indexes of insulin resistance. The lipoprotein insulin resistance (LPIR) score, a metabolomic marker, reflects the lipoprotein abnormalities observed in insulin-resistant states. The reliability of the LPIR score to predict IR in South Asians is currently unknown. In this study, we aimed to evaluate the predictive accuracy of LPIR compared to other fasting-based surrogate indices in SA.In a cross-sectional study of 59 non-diabetic SA subjects (age 36 ± 8 years, BMI 26.5 ± 5.2 kg/m2), we used calibration model analysis to assess the ability of the LPIR score and other simple surrogate indices [homeostasis model assessment (HOMA-IR), quantitative insulin sensitivity check index (QUICKI) and Adipose tissue insulin sensitivity (Adipo-SI)] to predict insulin sensitivity derived from the reference frequently sampled intravenous glucose tolerance test (FSIVGTT) and Minimal Model analysis (SiMM). LPIR scores were calculated using six lipoprotein particle concentrations and sizes measured by nuclear magnetic resonance (NMR) spectroscopy. Further, quantitative predictive accuracy and index comparisons were determined by root mean squared error (RMSE) of prediction and leave-one-out cross-validation-type RMSE of prediction (CVPE). Receiver operating characteristic (ROC) curve analysis was performed to determine how well LPIR distinguished insulin resistant individuals, categorized as an SiMM < 3.As determined by calibration model analysis, Adipo-SI, HOMA-IR, and QUICKI showed moderate correlations with for SiMM (Adipo-SI: r = 0.66; HOMA-IR: r = 0.60; QUICKI: r = 0.57, p = <0.0001). No significant differences were noted among CVPE or RMSE from any of the routinely used surrogate indices when compared with LPIR. The ROC area under the curve was 0.76 (95% CI 0.64–0.87) suggesting that LPIR performed well in identifying insulin resistant subjects. The optimal cut-off in IR individuals was LPIR >46 (sensitivity: 75.9 %, specificity: 70.0%). We conclude that NMR-derived LPIR may be an appropriate index to assess insulin resistance in South Asians.

MON-111 Plasma Insulin Measured with a Sensitive Immunoassay May Establish the Diagnosis of Congenital Hyperinsulinism Without Further Testing

Background: The diagnosis of congenital hyperinsulinism (CHI) is often hampered by a plasma insulin (p-insulin) detection limit of 2-3 mU/L (14-21 pmol/L) by RIA methods. Objective: To evaluate the diagnostic performance of a sensitive immunoassay for p-insulin and to find the optimal p-insulin cut-off for CHI versus other conditions with hypoglycaemia. Design: Single centre retrospective cohort study. Methods: Diagnostic tests with no medication, no i.v. glucose and under fasting conditions were performed in children with a clinical diagnosis of CHI. P-insulin concentrations determined at simultaneous p-glucose concentrations at least <3.2 mmol/L (57.5 mg/dL) were included in the analysis (n=61).The diagnosis of CHI was either clinical (n=61) or by gold standard criteria: hypoketotic hypoglycaemia plus disease-causing genetic mutations and/or diffuse, focal or atypical pancreatic histopathology (n=57). Samples from 15 children with idiopathic ketotic hypoglycaemia (IKH, diagnosis by exclusion, p-ketones >1.5 mmol/L during hypoglycaemia) were used as controls.P-insulin was measured by the high-sensitive assay (Cobas e411 immunoassay analyzer); lower detection limit 1.4 pmol/L (0.2 mU/L); normal range 18-173 pmol/L (2.57-24.7 mU/L). Concentrations <18 pmol/L were considered suppressed; ≥18 pmol/L un-suppressed.Receiver operating characteristics (ROC) curves with determination of area under the curve (AUC) values were performed for the diagnostic performance of p-insulin in the diagnosis of CHI. Results: In the 61 samples from CHI patients, the median (range) p-insulin was un-suppressed in all diagnostic samples [90; 20-758 pmol/L (12.9; 2.9-109.1 mU/L)], while p-insulin was suppressed in all 15 samples from IKH patients [1.5; 1.5-9 pmol/L (0.21; 0.21-1.3 mU/L)]. The ROC AUC was 1.0 (95%CI. 1.0-1.0) for the diagnosis of CHI defined both by the clinic and by gold standard. The optimal p-insulin cut-off was 14.5 pmol/L (2.1 mU/L) or 12.5 pmol/L (1.8 mU/L), for CHI patients by use of a simultaneous p-glucose cut-off of <3.2 mmol/L (57.5 mg/dL; n=61), or 3.0 mmol/L (55 mg/dL; n=49), respectively. Conclusions: The sensitive insulin assay performed excellent in diagnosing CHI with a ROC AUC of 1.0. The use of a p-insulin cut-off of 13 pmol/L (1.86 mU/L) during a diagnostic hypoketotic hypoglycaemia test may establish the diagnosis of CHI without further diagnostic testing.