Browsing by Subject "Insulin sensitivity"
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Item Association of Glycemia with Insulin Sensitivity and β-cell Function in Adults with Early Type 2 Diabetes on Metformin Alone(Elsevier, 2021) Utzschneider, Kristina M.; Younes, Naji; Rasouli, Neda; Barzilay, Joshua; Banerji, Mary Ann; Cohen, Robert M.; Gonzalez, Erica V.; Mather, Kieren J.; Ismail-Beigi, Faramarz; Raskin, Philip; Wexler, Deborah J.; Lachin, John M.; Kahn, Steven E.; GRADE Research Group; Medicine, School of MedicineAims: Evaluate the relationship between measures of glycemia with β-cell function and insulin sensitivity in adults with early type 2 diabetes mellitus (T2DM). Methods: This cross-sectional analysis evaluated baseline data from 3108 adults with T2DM <10 years treated with metformin alone enrolled in the Glycemia Reduction Approaches in Diabetes: A Comparative Effectiveness (GRADE) Study. Insulin and C-peptide responses and insulin sensitivity were calculated from 2-hour oral glucose tolerance tests. Regression models evaluated the relationships between glycemic measures (HbA1c, fasting and 2-hour glucose), measures of β-cell function and insulin sensitivity. Results: Insulin and C-peptide responses were inversely associated with insulin sensitivity. Glycemic measures were inversely associated with insulin and C-peptide responses adjusted for insulin sensitivity. HbA1c demonstrated modest associations with β-cell function (range: r −0.22 to −0.35). Fasting and 2-hour glucose were associated with early insulin and C-peptide responses (range: r −0.37 to −0.40) as well as late insulin and total insulin and C-peptide responses (range: r −0.50 to −0.60). Conclusion: Glycemia is strongly associated with β-cell dysfunction in adults with early T2DM treated with metformin alone. Efforts to improve glycemia should focus on interventions aimed at improving β-cell function.Item Characteristics of Obstructive Sleep Apnea Across the Spectrum of Glucose Tolerance in Obese Adolescents.(Frontiers Media, 2018-06-01) Hannon, Tamara S.; Watson, Sara E.; Jalou, Hasnaa E.; Chakravorty, Sangeeta; Mather, Kieren J.; Arslanian, Silva A.; Pediatrics, School of MedicineBackground: It is not known if dysglycemia and sleep-disordered breathing are linked in adolescents, as in adults. Objective: To perform a pilot study evaluating measures of sleep-disordered breathing across the spectrum of glucose tolerance in obese adolescents. We hypothesized that dysglycemia would be associated with sleep-disordered breathing. Participants/methods: This was a prospective, cross-sectional clinical pilot study that included 57 adolescents [body mass index (BMI) 38.9 ± 8.4 kg/m2] aged 12-18 years (14.5 ± 1.6) with normal glucose tolerance (NGT), or dysglycemia [impaired glucose tolerance (IGT) or type 2 diabetes (T2D)]. Measures: Anthropometrics, overnight polysomnogram, and oral glucose tolerance tests were performed. Participant characteristics and outcome measures were compared by glucose tolerance status. Correlational analyses were conducted to assess the associations between variables of interest. Results: Participants with dysglycemia (n = 21) were not different from those with NGT (n = 36) for BMI, waist circumference, body fat, or sleep characteristics. Nocturnal oxygen desaturation was associated with higher BMI (r = -0.334, p = 0.012). The apnea-hypopnea index (AHI) was not associated with physical and metabolic parameters. Although participants with dysglycemia tended to have higher AHIs (median 3.2, 2.2, and 1.6 events/h for T2D, IGT, and NGT, respectively), there was not a linear relationship between measures of glycemia and AHI. Conclusion: Further study with a larger proportion of youth with prediabetes and T2D is necessary to determine whether evaluation for sleep-disordered breathing is uniformly warranted.Item Circulating natriuretic peptide concentrations reflect changes in insulin sensitivity over time in the Diabetes Prevention Program(Springer, 2014-05) Walford, Geoffrey A.; Ma, Yong; Christophi, Costas A.; Goldberg, Ronald B.; Jarolim, Petr; Horton, Edward; Mather, Kieren J.; Barrett-Connor, Elizabeth; Davis, Jaclyn; Florez, Jose C.; Wang, Thomas J.; Department of Medicine, IU School of MedicineAIMS/HYPOTHESIS: We aimed to study the relationship between measures of adiposity, insulin sensitivity and N-terminal pro-B-type natriuretic peptide (NT-proBNP) in the Diabetes Prevention Program (DPP). METHODS: The DPP is a completed clinical trial. Using stored samples from this resource, we measured BMI, waist circumference (WC), an insulin sensitivity index (ISI; [1/HOMA-IR]) and NT-proBNP at baseline and at 2 years of follow-up in participants randomised to placebo (n = 692), intensive lifestyle intervention (n = 832) or metformin (n = 887). RESULTS: At baseline, log NT-proBNP did not differ between treatment arms and was correlated with baseline log ISI (p < 0.0001) and WC (p = 0.0003) but not with BMI (p = 0.39). After 2 years of treatment, BMI decreased in the lifestyle and metformin groups (both p < 0.0001); WC decreased in all three groups (p < 0.05 for all); and log ISI increased in the lifestyle and metformin groups (both p < 0.001). The change in log NT-proBNP did not differ in the lifestyle or metformin group vs the placebo group (p > 0.05 for both). In regression models, the change in log NT-proBNP was positively associated with the change in log ISI (p < 0.005) in all three study groups after adjusting for changes in BMI and WC, but was not associated with the change in BMI or WC after adjusting for changes in log ISI. CONCLUSION/INTERPRETATION: Circulating NT-proBNP was associated with a measure of insulin sensitivity before and during preventive interventions for type 2 diabetes in the DPP. This relationship persisted after adjustment for measures of adiposity and was consistent regardless of whether a participant was treated with placebo, intensive lifestyle intervention or metformin.Item Depressive symptoms and metabolic markers of risk for type 2 diabetes in obese adolescents(Wiley, 2013-11) Hannon, Tamara S.; Rofey, Dana L.; Lee, SoJung; Arslanian, Silva A.; Pediatrics, School of MedicineOBJECTIVE: Although higher rates of depression are found among individuals with type 2 diabetes, it remains unknown if the presence of depressive symptoms is associated with heightened metabolic risk for the development of type 2 diabetes among youth. The objective of this study was to evaluate whether depressive symptoms in obese adolescents are associated with impaired β-cell function relative to insulin sensitivity [oral disposition index (oDI)] and/or dysglycemia or prediabetes, predictors of type 2 diabetes development. RESEARCH DESIGN AND METHODS: Fasting and oral glucose tolerance test (OGTT)-derived indices of glucose tolerance, insulin sensitivity, secretion, and oDI were evaluated in obese youth (n = 56, age 15.0 ± 1.6 yr, 68% female). The Children's Depression Inventory was utilized to determine depressive symptomatology. RESULTS: Despite no association between depressive symptoms and measures of adiposity, youth with higher depressive symptoms had (i) significantly higher fasting and stimulated glucose levels (13% higher glucose area under the OGTT curve), (ii) ∼50% lower oDI, and (iii) a 50% frequency of prediabetes. CONCLUSIONS: These data point to an important relationship between depressive symptoms and a heightened metabolic risk for type 2 diabetes in obese adolescents, including prediabetes and impairment in β-cell function relative to insulin sensitivity. While the directionality of these relationships is unknown, it should be determined if treating one disorder improves the other or vice versa.Item Depressive symptoms are associated with fasting insulin resistance in obese youth(Wiley Online Library, 2014-10) Hannon, Tamara S.; Li, Zhuokai; Tu, Wanzhu; Humber, Jordan N.; Carroll, Aaron E.; Lagges, Ann M.; Gupta, Sandeep; Department of Pediatrics, School of MedicineBACKGROUND: In adults, depressive symptoms are positively associated with insulin resistance. OBJECTIVE: To determine whether an association exists between depressive symptoms and markers of insulin resistance in youth. METHODS: This study used a retrospective review of data from an obesity clinic. We evaluated the association between depressive symptoms (Children's Depression Inventory, CDI) and fasting insulin and homeostatic model assessment-insulin resistance (HOMA-IR) in obese youth (n = 207, age 10-18 years). Individuals with lower vs. higher CDI T-scores (<65 vs. ≥65) were compared; this cut-point is accepted as indicating the possibility of clinical depression. Multiple linear regression was used to evaluate relationships between CDI T-scores and insulin resistance. RESULTS: Fasting insulin and HOMA-IR values were 40% higher in patients with higher CDI T-scores (P = 0.04). After accounting for gender, race, age and body mass index, CDI T-score remained associated with HOMA-IR, although the strength of the association was small (b = 0.007, P = 0.049). CONCLUSIONS: Relationships between depressive symptoms and insulin resistance should be considered when evaluating obese youth.Item Doc2b enrichment enhances glucose homeostasis in mice via potentiation of insulin secretion and peripheral insulin sensitivity.(Springer, 2014-07) Ramalingam, Latha; Oh, Eunjin; Thurmond, Debbie C.; Biochemistry & Molecular Biology, School of MedicineAIMS/HYPOTHESIS: Insulin secretion from pancreatic beta cells and insulin-stimulated glucose uptake into skeletal muscle are processes regulated by similar isoforms of the soluble N-ethylmaleimide-sensitive factor-attachment protein receptor (SNARE) and mammalian homologue of unc-18 (Munc18) protein families. Double C2 domain β (Doc2b), a SNARE- and Munc18-interacting protein, is implicated as a crucial effector of glycaemic control. However, whether Doc2b is naturally limiting for these processes, and whether Doc2b enrichment might exert a beneficial effect upon glycaemia in vivo, remains undetermined. METHODS: Tetracycline-repressible transgenic (Tg) mice engineered to overexpress Doc2b simultaneously in the pancreas, skeletal muscle and adipose tissues were compared with wild-type (Wt) littermate mice regarding glucose and insulin tolerance, islet function in vivo and ex vivo, and skeletal muscle GLUT4 accumulation in transverse tubule/sarcolemmal surface membranes. SNARE complex formation was further assessed using Doc2b overexpressing L6-GLUT4-myc myoblasts to derive mechanisms relatable to physiological in vivo analyses. RESULTS: Doc2b Tg mice cleared glucose substantially faster than Wt mice, correlated with enhancements in both phases of insulin secretion and peripheral insulin sensitivity. Heightened peripheral insulin sensitivity correlated with elevated insulin-stimulated GLUT4 vesicle accumulation in cell surface membranes of Doc2b Tg mouse skeletal muscle. Mechanistic studies demonstrated Doc2b enrichment to enhance syntaxin-4-SNARE complex formation in skeletal muscle cells. CONCLUSIONS/INTERPRETATION: Doc2b is a limiting factor in SNARE exocytosis events pertinent to glycaemic regulation in vivo. Doc2b enrichment may provide a novel means to simultaneously boost islet and skeletal muscle function in vivo in the treatment and/or prevention of diabetes.Item DOC2B promotes insulin sensitivity in mice via a novel KLC1-dependent mechanism in skeletal muscle(Springer Verlag, 2019-05) Zhang, Jing; Oh, Eunjin; Merz, Karla E.; Aslamy, Arianne; Veluthakal, Rajakrishnan; Salunkhe, Vishal A.; Ahn, Miwon; Tunduguru, Ragadeepthi; Thurmond, Debbie C.; Cellular and Integrative Physiology, School of MedicineAims/hypothesis: Skeletal muscle accounts for >80% of insulin-stimulated glucose uptake; dysfunction of this process underlies insulin resistance and type 2 diabetes. Insulin sensitivity is impaired in mice deficient in the double C2 domain β (DOC2B) protein, while whole-body overexpression of DOC2B enhances insulin sensitivity. Whether insulin sensitivity in the skeletal muscle is affected directly by DOC2B or is secondary to an effect on other tissues is unknown; the underlying molecular mechanisms also remain unclear. Methods: Human skeletal muscle samples from non-diabetic or type 2 diabetic donors were evaluated for loss of DOC2B during diabetes development. For in vivo analysis, new doxycycline-inducible skeletal-muscle-specific Doc2b-overexpressing mice fed standard or high-fat diets were evaluated for insulin and glucose tolerance, and insulin-stimulated GLUT4 accumulation at the plasma membrane (PM). For in vitro analyses, a DOC2B-overexpressing L6-GLUT4-myc myoblast/myotube culture system was coupled with an insulin resistance paradigm. Biochemical and molecular biology methods such as site-directed mutagenesis, co-immunoprecipitation and mass spectrometry were used to identify the molecular mechanisms linking insulin stimulation to DOC2B. Results: We identified loss of DOC2B (55% reduction in RNA and 40% reduction in protein) in the skeletal muscle of human donors with type 2 diabetes. Furthermore, inducible enrichment of DOC2B in skeletal muscle of transgenic mice enhanced whole-body glucose tolerance (AUC decreased by 25% for female mice) and peripheral insulin sensitivity (area over the curve increased by 20% and 26% for female and male mice, respectively) in vivo, underpinned by enhanced insulin-stimulated GLUT4 accumulation at the PM. Moreover, DOC2B enrichment in skeletal muscle protected mice from high-fat-diet-induced peripheral insulin resistance, despite the persistence of obesity. In L6-GLUT4-myc myoblasts, DOC2B enrichment was sufficient to preserve normal insulin-stimulated GLUT4 accumulation at the PM in cells exposed to diabetogenic stimuli. We further identified that DOC2B is phosphorylated on insulin stimulation, enhancing its interaction with a microtubule motor protein, kinesin light chain 1 (KLC1). Mutation of Y301 in DOC2B blocked the insulin-stimulated phosphorylation of DOC2B and interaction with KLC1, and it blunted the ability of DOC2B to enhance insulin-stimulated GLUT4 accumulation at the PM. Conclusions/interpretation: These results suggest that DOC2B collaborates with KLC1 to regulate insulin-stimulated GLUT4 accumulation at the PM and regulates insulin sensitivity. Our observation provides a basis for pursuing DOC2B as a novel drug target in the muscle to prevent/treat type 2 diabetes.Item Early Impairment of Insulin Sensitivity, β-Cell Responsiveness, and Insulin Clearance in Youth with Stage 1 Type 1 Diabetes(Oxford University Press, 2021) Galderisi, Alfonso; Moran, Antoinette; Evans-Molina, Carmella; Martino, Mariangela; Santoro, Nicola; Caprio, Sonia; Cobelli, Claudio; Pediatrics, School of MedicineContext: Clinical onset of type 1 diabetes (Stage 3 T1D) is preceded by a presymptomatic phase characterized by multiple islet autoantibodies with normal glucose tolerance (Stage 1 T1D). Objective: The aim was to explore the metabolic phenotypes of β-cell function and insulin sensitivity and clearance in normoglycemic youth with Stage 1 T1D and compare them with healthy nonrelated peers during a 3-hour oral glucose tolerance test (OGTT). Methods: Twenty-eight lean youth, 14 with ≥2 islet autoantibodies (cases) and 14 healthy controls underwent a 3-hour 9-point OGTT with measurement of glucose, C-peptide, and insulin. The oral minimal model was used to quantitate β-cell responsiveness (φtotal) and insulin sensitivity (SI), allowing assessment of β-cell function by the disposition index (DI=φtotal×SI). Fasting insulin clearance (CL0) was calculated as the ratio between the fasting insulin secretion rate (ISR) and plasma insulin levels (ISR0/I0), while postload clearance (CL180) was estimated by the ratio of AUC of ISR over the plasma insulin AUC for the 3-hour OGTT (ISRAUC/IAUC). Participants with impaired fasting glucose, impaired glucose tolerance, or any OGTT glucose concentration ≥200 mg/dL were excluded. Results: Cases (10.5 years [8, 15]) exhibited reduced DI (P < .001) due to a simultaneous reduction in both φtotal (P < 0.001) and SI (P = .008) compared with controls (11.5 years [10.4, 14.9]). CL0 and CL180 were lower in cases than in controls (P = .005 and P = .019). Conclusion: Presymptomatic Stage 1 T1D in youth is associated with reduced insulin sensitivity and lower β-cell responsiveness, and the presence of blunted insulin clearance.Item LBSUN309 The Effect Of Prebiotics In Newly Diagnosed Youth With Type 1 Diabetes (T1D)(Oxford University Press, 2022-11-01) Ismail, Heba; Evans-Molina, Carmella; DiMeglio, Linda A.; Pediatrics, School of MedicineAcetylated and butyrylated high amylose starch (HAMS-AB) is a prebiotic that is effective in T1D prevention in mouse models. It alters the gut microbiome profile towards bacterial fermenters with increases short chain fatty acids (SCFA) production which improves glycemia, insulin sensitivity and secretion. The objective of this pilot study is to assess the effect of oral HAMS-AB for 4 weeks on glycemia, microbial metabolite and SCFA production in newly diagnosed (<2 years of diagnosis) youth with T1D. Thus far, we have enrolled 7 subjects with 1 early drop out due to nausea secondary to the prebiotic. The mean±SD age in the remaining 6 was 14.4±1.8 yrs, diabetes duration 18.6±6.3 months, 4/6 were female and White, all with BMI of <85th%. The prebiotic was safe and well-tolerated in all 6 who remained in the study. We assessed glycemia changes pre and post-intervention and the percent time in range (TIR) from continuous glucose monitoring data over a 4 week period increased significantly: 61. 0% vs. 71.8%, X2 18.2, p=0. 001. Stool SCFA levels were measured in 4 subjects, and butyrate levels increased post-prebiotic (8.1±9.8 vs 22.6± 6.4mmol SCFA/kg fecal material, p=0. 047). Serum and plasma Hippurate levels (a microbial metabolite associated with increased gut bacterial diversity and improved glycemia) increased significantly after 4 weeks of prebiotic consumption compared to before in all 6 individuals (p=0. 028 for serum and p=0. 033 for plasma, respectively). In summary, the prebiotic HAMS-AB was safe in adolescents with T1D. It significantly increased the percent TIR, serum and plasma Hippurate levels and stool butyrate levels. Enrollment continues as collection of samples from more participants should allow for a more conclusive analysis.Item The linearized disposition index augments understanding of treatment effects in diabetes(American Physiological Society, 2021) Kile, Amanda J.; Hanna, Clarissa; Hannon, Tamara S.; Kirkman, M. Sue; Considine, Robert V.; Patel, Yash; Mather, Kieren J.; Medicine, School of MedicineThe disposition index, calculated by multiplying measures of insulin secretion and insulin sensitivity, is widely applied as a sensitivity-adjusted measure of insulin secretion. We have recently shown that linearizing the underlying relationship uniquely permits identification of terms relating to maximal insulin secretion capacity and the secretion-coupling relationship, with both terms separately contributing to differences in the secretion-sensitivity relationship across gradations of glycemia. Here, we demonstrate the application of this linearized equation to the evaluation of treatment-induced changes in the insulin secretion-sensitivity relationship. We applied a combination of repeated-measures multivariate linear regression (evaluating treatment-induced changes in the joint relationship of insulin sensitivity and secretion) plus mixed-model repeated measures (evaluating treatment effects on maximal secretion capacity and on the secretion-sensitivity coupling slope) and compared against a usual application of the disposition index calculated from the same measurements. This novel approach allows a more informative description of treatment-induced changes compared with the usual disposition index, including isolating the source of change within the mutually adjusted relationship and identifying treatment-induced changes in the secretion-sensitivity coupling slope and in maximal insulin secretion. Application of this linearized approach provides an expanded understanding of treatment-induced changes in the insulin sensitivity-secretion relationship. NEW & NOTEWORTHY: The linearized insulin secretion-sensitivity relationship allows separate evaluation of the secretion-sensitivity slope and of maximal insulin secretion. Here, we demonstrate the application of this methodology to the evaluation of clinical trial data, showing that it provides an expanded understanding of treatment-induced changes compared with the disposition index.