| 1. |
- Schriever, Sonja C., et al.
(författare)
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Type 2 diabetes risk gene Dusp8 regulates hypothalamic Jnk signaling and insulin sensitivity
- 2020
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Ingår i: Journal of Clinical Investigation. - 0021-9738. ; 130:11, s. 6093-6108
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Tidskriftsartikel (refereegranskat)abstract
- Recent genome-wide association studies (GWAS) identified DUSP8, encoding a dual-specificity phosphatase targeting mitogen-activated protein kinases, as a type 2 diabetes (T2D) risk gene. Here, we reveal that Dusp8 is a gatekeeper in the hypothalamic control of glucose homeostasis in mice and humans. Male, but not female, Dusp8 loss-of-function mice, either with global or corticotropin-releasing hormone neuron–specific deletion, had impaired systemic glucose tolerance and insulin sensitivity when exposed to high-fat diet (HFD). Mechanistically, we found impaired hypothalamic-pituitary-adrenal axis feedback, blunted sympathetic responsiveness, and chronically elevated corticosterone levels driven by hypothalamic hyperactivation of Jnk signaling. Accordingly, global Jnk1 ablation, AAV-mediated Dusp8 overexpression in the mediobasal hypothalamus, or metyrapone-induced chemical adrenalectomy rescued the impaired glucose homeostasis of obese male Dusp8-KO mice, respectively. The sex-specific role of murine Dusp8 in governing hypothalamic Jnk signaling, insulin sensitivity, and systemic glucose tolerance was consistent with functional MRI data in human volunteers that revealed an association of the DUSP8 rs2334499 risk variant with hypothalamic insulin resistance in men. Further, expression of DUSP8 was increased in the infundibular nucleus of T2D humans. In summary, our findings suggest the GWAS-identified gene Dusp8 as a novel hypothalamic factor that plays a functional role in the etiology of T2D.
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| 2. |
- Dietz, Benedikt, et al.
(författare)
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Detection of diabetes from whole-body MRI using deep learning
- 2021
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Ingår i: JCI Insight. - : American Society for Clinical Investigation. - 2379-3708. ; 6:21
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Tidskriftsartikel (refereegranskat)abstract
- Obesity is one of the main drivers of type 2 diabetes, but it is not uniformly associated with the disease. The location of fat accumulation is critical for metabolic health. Specific patterns of body fat distribution, such as visceral fat, are closely related to insulin resistance. There might be further, hitherto unknown, features of body fat distribution that could additionally contribute to the disease. We used machine learning with dense convolutional neural networks to detect diabetes-related variables from 2371 T1-weighted whole-body MRI data sets. MRI was performed in participants undergoing metabolic screening with oral glucose tolerance tests. Models were trained for sex, age, BMI, insulin sensitivity, HbA1c, and prediabetes or incident diabetes. The results were compared with those of conventional models. The area under the receiver operating characteristic curve was 87% for the type 2 diabetes discrimination and 68% for prediabetes, both superior to conventional models. Mean absolute regression errors were comparable to those of conventional models. Heatmaps showed that lower visceral abdominal regions were critical in diabetes classification. Subphenotyping revealed a group with high future diabetes and microalbuminuria risk. Our results show that diabetes is detectable from whole-body MRI without additional data. Our technique of heatmap visualization identifies plausible anatomical regions and highlights the leading role of fat accumulation in the lower abdomen in diabetes pathogenesis.
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| 3. |
- Heni, Martin, et al.
(författare)
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Interaction between the obesity-risk gene FTO and the dopamine D2 receptor gene ANKK1/TaqIA on insulin sensitivity
- 2016
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Ingår i: Diabetologia. - : Springer Science and Business Media LLC. - 0012-186X .- 1432-0428. ; 59:12, s. 2622-2631
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Tidskriftsartikel (refereegranskat)abstract
- Aims/hypothesis: Variations in FTO are the strongest common genetic determinants of adiposity, and may partly act by influencing dopaminergic signalling in the brain leading to altered reward processing that promotes increased food intake. Therefore, we investigated the impact of such an interaction on body composition, and peripheral and brain insulin sensitivity. Methods: Participants from the Tübingen Family study (n = 2245) and the Malmö Diet and Cancer study (n = 2921) were genotyped for FTO SNP rs8050136 and ANKK1 SNP rs1800497. Insulin sensitivity in the caudate nucleus, an important reward area in the brain, was assessed by fMRI in 45 participants combined with intranasal insulin administration. Results: We found evidence of an interaction between variations in FTO and an ANKK1 polymorphism that associates with dopamine (D2) receptor density. In cases of reduced D2 receptor availability, as indicated by the ANKK1 polymorphism, FTO variation was associated with increased body fat and waist circumference and reduced peripheral insulin sensitivity. Similarly, altered central insulin sensitivity was observed in the caudate nucleus in individuals with the FTO obesity-risk allele and diminished D2 receptors. Conclusions/interpretation: The effects of variations in FTO are dependent on dopamine D2 receptor density (determined by the ANKK1 polymorphism). Carriers of both risk alleles might, therefore, be at increased risk of obesity and diabetes.
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| 4. |
- Nead, Kevin T., et al.
(författare)
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Contribution of common non-synonymous variants in PCSK1 to body mass index variation and risk of obesity : a systematic review and meta-analysis with evidence from up to 331 175 individuals
- 2015
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Ingår i: Human Molecular Genetics. - : Oxford University Press (OUP). - 0964-6906 .- 1460-2083. ; 24:12, s. 3582-3594
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Tidskriftsartikel (refereegranskat)abstract
- Polymorphisms rs6232 and rs6234/rs6235 in PCSK1 have been associated with extreme obesity [e.g. body mass index (BMI) a parts per thousand yen 40 kg/m(2)], but their contribution to common obesity (BMI a parts per thousand yen 30 kg/m(2)) and BMI variation in a multi-ethnic context is unclear. To fill this gap, we collected phenotypic and genetic data in up to 331 175 individuals from diverse ethnic groups. This process involved a systematic review of the literature in PubMed, Web of Science, Embase and the NIH GWAS catalog complemented by data extraction from pre-existing GWAS or custom-arrays in consortia and single studies. We employed recently developed global meta-analytic random-effects methods to calculate summary odds ratios (OR) and 95% confidence intervals (CIs) or beta estimates and standard errors (SE) for the obesity status and BMI analyses, respectively. Significant associations were found with binary obesity status for rs6232 (OR = 1.15, 95% CI 1.06-1.24, P = 6.08 x 10(-6)) and rs6234/rs6235 (OR = 1.07, 95% CI 1.04-1.10, P = 3.00 x 10(-7)). Similarly, significant associations were found with continuous BMI for rs6232 (beta = 0.03, 95% CI 0.00-0.07; P = 0.047) and rs6234/rs6235 (beta = 0.02, 95% CI 0.00-0.03; P = 5.57 x 10(-4)). Ethnicity, age and study ascertainment significantly modulated the association of PCSK1 polymorphisms with obesity. In summary, we demonstrate evidence that common gene variation in PCSK1 contributes to BMI variation and susceptibility to common obesity in the largest known meta-analysis published to date in genetic epidemiology.
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| 5. |
- Prystupa, Katsiaryna, et al.
(författare)
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Comprehensive validation of fasting-based and oral glucose tolerance test-based indices of insulin secretion against gold standard measures
- 2022
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Ingår i: BMJ Open Diabetes Research & Care. - : BMJ Publishing Group Ltd. - 2052-4897. ; 10:5
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Tidskriftsartikel (refereegranskat)abstract
- INTRODUCTION: With pre-diabetes and diabetes increasingly recognized as heterogeneous conditions, assessment of beta-cell function is gaining clinical importance to identify disease subphenotypes. Our study aims to comprehensively validate all types of surrogate indices based on oral glucose tolerance test (OGTT) and fasting measurements in comparison with gold standard methods.RESEARCH DESIGN AND METHODS: The hyperglycemic clamp extended with glucagon-like peptide 1 (GLP-1) infusion and intravenous glucose tolerance test (IVGTT), as well as OGTT, was performed in two well-phenotyped cohorts. The gold standard-derived indices were compared with surrogate insulin secretion markers, derived from fasting state and OGTT, using both Pearson's and Spearman's correlation coefficients. The insulin-based and C-peptide-based indices were analyzed separately in different groups of glucose tolerance and the entire cohorts.RESULTS: The highest correlation coefficients were found for area under curve (AUC) (I0-30)/AUC (G0-30), I30/G30, first-phase Stumvoll and Kadowaki model. These indices have high correlation coefficients with measures obtained from both insulin and C-peptide levels from IVGTT and hyperglycemic clamp. AUC (I0-120)/AUC (G0-120), BIGTT-AIR0-60-120, I30/G30, first-phase Stumvoll and AUC (I0-30)/AUC (G0-30) demonstrated the strongest association with incretin-stimulated insulin response.CONCLUSIONS: We have identified glucose-stimulated and GLP-1-stimulated insulin secretion indices, derived from OGTT and fasting state, that have the strongest correlation with gold standard measures and could be potentially used in future researches and clinical practice.
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| 6. |
- Renklint, Rebecka, et al.
(författare)
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Surrogate measures of first-phase insulin secretion versus reference methods intravenous glucose tolerance test and hyperglycemic clamp : a systematic review and meta-analyses
- 2024
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Ingår i: BMJ Open Diabetes Research & Care. - : BMJ Publishing Group Ltd. - 2052-4897. ; 12:4
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: In this systematic review, we investigated the diagnostic accuracy of surrogate measures of insulin secretion based on fasting samples and the oral glucose tolerance test (OGTT). The first phase of insulin secretion was calculated using two gold standard methods; the hyperglycemic clamp (HGC) test and intravenous glucose tolerance test (IVGTT).Research design and methods: We conducted searches in the PubMed, Cochrane Central, and Web of Science databases, the last of which was conducted at the end of June 2021. Studies were included that measured first-phase insulin secretion in adults using both a gold-standard reference method (either HGC or IVGTT) and one or more surrogate measures from either fasting samples, OGTT or a meal-tolerance test. QUADAS-2, a revised tool for the quality assessment of diagnostic accuracy studies, was used for quality assessment. Random-effects meta-analyses were performed to examine the correlation between first-phase measured with gold standard and surrogate methods.Results: A total of 33 articles, encompassing 5362 individuals with normal glucose tolerance, pre-diabetes or type 2 diabetes, were included in our systematic review. Homeostatic model assessment (HOMA)-beta and Insulinogenic Index 30 (IGI(30)) were the surrogate measures validated in the largest number of studies (17 and 13, respectively). HOMA-beta's pooled correlation to the reference methods was 0.48 (95% CI 0.40 to 0.56) The pooled correlation of IGI to the reference methods was 0.61 (95% CI 0.54 to 0.68). The surrogate measures with the highest correlation to the reference methods were Kadowaki (0.67 (95% CI 0.61 to 0.73)) and Stumvoll's first-phase secretion (0.65 (95% CI 0.58 to 0.71)), both calculated from an OGTT.Conclusions: Surrogate measures from the first 30 min of an OGTT capture the first phase of insulin secretion and are a good choice for epidemiological studies. HOMA-beta has a moderate correlation to the reference methods but is not a measure of the first phase specifically.
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| 7. |
- Wagner, Róbert, et al.
(författare)
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Nonsuppressed glucagon after glucose challenge as a potential predictor for glucose tolerance
- 2017
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Ingår i: Diabetes. - : American Diabetes Association. - 0012-1797 .- 1939-327X. ; 66:5, s. 1373-1379
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Tidskriftsartikel (refereegranskat)abstract
- Glucagon levels are classically suppressed after glucose challenge. It is still not clear as to whether a lack of suppression contributes to hyperglycemia and thus to the development of diabetes. We investigated the association of postchallenge change in glucagon during oral glucose tolerance tests (OGTTs), hypothesizing that higher postchallenge glucagon levels are observed in subjects with impaired glucose tolerance (IGT). Glucagon levels were measured during OGTT in a total of 4,194 individuals without diabetes in three large European cohorts. Longitudinal changes in glucagon suppression were investigated in 50 participants undergoing a lifestyle intervention. Only 66-79% of participants showed suppression of glucagon at 120 min (fold change glucagon120/0 <1) during OGTT, whereas 21-34% presented with increasing glucagon levels (fold change glucagon120/0 ≥1). Participants with nonsuppressed glucagon120 had a lower risk of IGT in all cohorts (odds ratio 0.44-0.53, P < 0.01). They were also leaner and more insulin sensitive and had lower liver fat contents. In the longitudinal study, an increase of fold change glucagon120/0 was associated with an improvement in insulin sensitivity (P = 0.003). We characterize nonsuppressed glucagon120 during the OGTT. Lower glucagon suppression after oral glucose administration is associated with a metabolically healthier phenotype, suggesting that it is not an adverse phenomenon.
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