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Context: Detecting patients with surgically curable aldosterone-producing adenoma (APA) among hypertensive individuals is clinically pivotal. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) is the ideal method of measuring plasma aldosterone concentration (PAC) because of the inaccuracy of conventional chemiluminescent enzyme immunoassay (CLEIA). However, LC-MS/MS is expensive and requires expertise. We have developed a novel noncompetitive CLEIA (NC-CLEIA) for measuring PAC in 30 minutes. Objective: This work aimed to validate NC-CLEIA PAC measurements by comparing them with LC-MS/MS measurements and determining screening cutoffs for both measurements detecting APA. Methods: We retrospectively measured PAC using LC-MS/MS and NC-CLEIA in 133 patients with APA, 100 with bilateral hyperaldosteronism, and 111 with essential hypertension to explore the accuracy of NC-CLEIA PAC measurements by comparing with LC-MS/MS measurements and determined the cutoffs for detecting APA. Results: Passing-Bablok analysis revealed that the values by NC-CLEIA (the regression slope, intercept, and correlation coefficient were 0.962, -0.043, and 0.994, respectively) were significantly correlated and equivalent to those by LC-MS/MS. Bland-Altman plot analysis of NC-CLEIA and LC-MS/MS also demonstrated smaller systemic errors (a bias of -0.348 ng/dL with limits of agreement of -4.390 and 3.694 within a 95% CI) in NC-CLEIA than LC-MS/MS. The receiver operating characteristic analysis demonstrated that cutoff values for aldosterone/renin activity ratio obtained by LC-MS/MS and NC-CLEIA were 31.2 and 31.5 (ng/dL per ng/mL/hour), with a sensitivity of 91.0% and 90.2% and specificity of 75.4% and 76.8%, respectively, to differentiate APA from non-APA. Conclusion: This newly developed NC-CLEIA for measuring PAC could serve as a clinically reliable alternative to LC-MS/MS.
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AIMS/INTRODUCTION: Insulin resistance syndrome and lipoatrophic diabetes are rare conditions characterized by the development of treatment-refractory diabetes with severe insulin resistance. We recently conducted a 24 week, multicenter, single-arm trial (EMPIRE-01) that demonstrated a certain level of effectiveness and safety of empagliflozin for these conditions. To evaluate treatment safety over a longer period, we have now performed an additional 28 week trial (EMPIRE-02) that followed on from EMPIRE-01. MATERIALS AND METHODS: The primary and secondary outcomes were safety and efficacy evaluations, respectively. All eight subjects of the EMPIRE-01 trial participated in EMPIRE-02. RESULTS: Twenty adverse events (AEs) were recorded among five individuals during the combined 52 week treatment period of both trials. Whereas one case of chronic hepatitis B was moderate in severity, all other AEs were mild. There were thus no serious AEs or events necessitating discontinuation or suspension of treatment or a reduction in drug dose. Whereas ketoacidosis or marked increases in serum ketone body levels were not observed, the mean body mass of the subjects was decreased slightly after completion of EMPIRE-02. The improvement in mean values of glycemic parameters observed in EMPIRE-01 was not sustained in EMPIRE-02, mostly because of one individual whose parameters deteriorated markedly, likely as a result of nonadherence to diet therapy. The improvement in glycemic parameters was sustained during EMPIRE-02 after exclusion of this subject from analysis. CONCLUSIONS: Empagliflozin demonstrated a certain level of safety and efficacy for the treatment of insulin resistance syndrome and lipoatrophic diabetes over 52 weeks, confirming its potential as a therapeutic option.
ABSTRACT
The measurement evolution enabled more accurate evaluation of aldosterone production in hypertensive patients. However, the cut-off values for novel assays have been not sufficiently validated. The present study was undertaken to validate the novel chemiluminescent enzyme immunoassay for aldosterone in conjunction with other methods. Moreover, we also aimed to establish a new cut-off value for primary aldosteronism in the captopril challenge test using the novel assay. First, we collected 390 plasma samples, in which aldosterone levels measured using liquid chromatography-mass spectrometry ranged between 0.18 and 1346 ng/dL. The novel chemiluminescent enzyme immunoassay showed identical correlation of plasma aldosterone with liquid chromatography-mass spectrometry, in contrast to conventional radioimmunoassay. Further, we enrolled 299 and 39 patients with primary aldosteronism and essential hypertension, respectively. Plasma aldosterone concentrations measured using the novel assay were lower than those measured by radioimmunoassay, which resulted in decreased aldosterone-to-renin ratios. Subsequently, positive results of the captopril challenge test based on radioimmunoassay turned into "negative" based on the novel assay in 45% patients with primary aldosteronism, using the conventional cut-off value (aldosterone-to-renin activity ratio > 20 ng/dL per ng/mL/h). Receiver operating characteristic curve analysis demonstrated that aldosterone-to-renin activity ratios > 8.2 ng/dL per ng/mL/h in the novel assay was compatible with the conventional diagnosis (sensitivity, 0.874; specificity, 0.980). Our study indicates the great measurement accuracy of the novel chemiluminescent enzyme immunoassay for aldosterone, and the importance of measurement-adjusted cut-offs in the diagnosis of primary aldosteronism.
Subject(s)
Aldosterone , Captopril , Hyperaldosteronism , Luminescent Measurements , Humans , Hyperaldosteronism/diagnosis , Hyperaldosteronism/blood , Male , Female , Middle Aged , Aldosterone/blood , Retrospective Studies , Adult , Aged , Luminescent Measurements/methods , Immunoenzyme Techniques/methods , Hypertension/blood , Hypertension/diagnosis , Renin/blood , Cohort Studies , RadioimmunoassayABSTRACT
Background: Multiple acyl-CoA dehydrogenase deficiency (MADD) is an inherited metabolic disorder caused by biallelic pathogenic variants in genes related to the flavoprotein complex. Dysfunction of the complex leads to impaired fatty acid oxidation and ketone body production which can cause hypoketotic hypoglycemia with prolonged fasting. Patients with fatty acid oxidation disorders (FAODs) such as MADD are treated primarily with a dietary regimen consisting of high-carbohydrate foods and avoidance of prolonged fasting. However, information on the long-term sequelae associated with this diet have not been accumulated. In general, high-carbohydrate diets can induce diseases such as type 2 diabetes mellitus (T2DM), although few patients with both MADD and T2DM have been reported. Case: We present the case of a 32-year-old man with MADD who was on a high-carbohydrate diet for >30 years and exhibited symptoms resembling diabetic ketoacidosis. He presented with polydipsia, polyuria, and weight loss with a decrease in body mass index from 31 to 25 kg/m2 over 2 months. Laboratory tests revealed a HbA1c level of 13.9%; however, the patient did not show metabolic acidosis but only mild ketosis. Discussion/conclusion: This report emphasizes the potential association between long-term adherence to high-carbohydrate dietary therapy and T2DM development. Moreover, this case underscores the difficulty of detecting diabetic ketosis in patients with FAODs such as MADD due to their inability to produce ketone bodies. These findings warrant further research of the long-term complications associated with this diet as well as warning of the potential progression of diabetes in patients with FAODs such as MADD.
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INTRODUCTION: Insulin resistance syndrome and lipoatrophic diabetes are characterized by severe insulin resistance and are often refractory to treatment. Trials assessing the efficacy of antidiabetes drugs for these rare conditions have been limited, however. Sodium-glucose cotransporter 2 (SGLT2) inhibitors, which lower glycemia independently of insulin action, have shown efficacy for type 2 diabetes with insulin resistance. We here investigated the efficacy and safety of the SGLT2 inhibitor empagliflozin for treatment of insulin resistance syndrome and lipoatrophic diabetes. METHODS: The trial was conducted at five academic centers in Japan and included seven patients with insulin resistance syndrome and one patient with lipoatrophic diabetes. Participants received 10 mg of empagliflozin daily. If the hemoglobin A1c (HbA1c) level was ≥ 7.0% (52 mmol/mol) after 12 weeks, the dose was adjusted to 25 mg. The study duration was 24 weeks, and the primary outcome was the change in HbA1c level by the end of the treatment period. Safety evaluations were performed for all participants. RESULTS: By the end of the 24-week treatment period, the mean HbA1c level for all eight patients had decreased by 0.99 percentage points (10.8 mmol/mol) (95% confidence interval [CI], 0.59 to 1.38 percentage points, 6.6 to 14.9 mmol/mol) and the mean fasting plasma glucose concentration had declined by 63.9 mg/dL (3.55 mmol/L) (95% CI 25.5 to 102.3 mg/dL, 1.42 to 5.68 mmol/L). Continuous glucose monitoring revealed a reduction in mean glucose levels from 164.3 ± 76.1 to 137.6 ± 46.6 mg/dL (9.13 ± 4.23 to 7.65 ± 2.59 mmol/L) as well as an increase in the time in range (70-180 mg/dL) from 58.9 ± 36.1% to 70.8 ± 18.3%. Seventeen mild adverse events were recorded in five individuals throughout the study period. No severe events were reported. The mean body mass showed a slight decrease and the mean serum ketone body concentration showed a slight increase during treatment. CONCLUSION: Our results demonstrate that empagliflozin shows a certain level of efficacy and safety for treatment of insulin resistance syndrome and lipoatrophic diabetes. TRIAL REGISTRATION: jRCTs2051190029 and NCT04018365.
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The liver synthesizes and releases bile acids into the gut. Bile acids, either directly or indirectly, inhibit agouti-related peptide (AGRP)-B cells in the pars tuberalis of the pituitary gland. AGRP-B cells are assumed to promote pancreatic insulin secretion and/or to improve insulin sensitivities in insulin sensitive organs, resulting in improved glucose tolerance.
Subject(s)
Insulin , Pituitary Gland , Humans , Agouti-Related Protein/metabolism , Pituitary Gland/metabolism , Insulin/metabolism , Glucose/metabolism , Bile Acids and SaltsABSTRACT
OBJECTIVE: Promoting thermogenesis in adipose tissue has been a promising strategy against obesity and related metabolic complications. We aimed to identify compounds that promote thermogenesis in adipocytes and to elucidate their functions and roles in metabolism. METHODS: To identify compounds that directly promote thermogenesis from a structurally diverse set of 4800 compounds, we utilized a cell-based platform for high-throughput screening that induces uncoupling protein 1 (Ucp1) expression in adipocytes. RESULTS: We identified one candidate compound that activates UCP1. Additional characterization of this compound revealed that it induced cellular thermogenesis in adipocytes with negligible cytotoxicity. In a subsequent diet-induced obesity model, mice treated with this compound exhibited a slower rate of weight gain, improved insulin sensitivity, and increased energy expenditure. Mechanistic studies have revealed that this compound increases mitochondrial biogenesis by elevating maximal respiration, which is partly mediated by the protein kinase A (PKA)-p38 mitogen-activated protein kinase (MAPK) signaling pathway. A further comprehensive genetic analysis of adipocytes treated with these compounds identified two novel UCP1-dependent thermogenic genes, potassium voltage-gated channel subfamily C member 2 (Kcnc2) and predicted gene 5627 (Gm5627). CONCLUSIONS: The identified compound can serve as a potential therapeutic drug for the treatment of obesity and its related metabolic disorders. Furthermore, our newly clarified thermogenic genes play an important role in UCP1-dependent thermogenesis in adipocytes.
Subject(s)
Insulin Resistance , Obesity , Uncoupling Protein 1 , Animals , Mice , Adipocytes/metabolism , Adipose Tissue/metabolism , Adipose Tissue, Brown/metabolism , Energy Metabolism , Obesity/complications , Obesity/drug therapy , Thermogenesis/physiology , Uncoupling Protein 1/antagonists & inhibitorsABSTRACT
Metabolism in each organ of multi-organ organisms, including humans, is regulated in a coordinated manner to dynamically maintain whole-body homeostasis. Metabolic information exchange among organs/tissues, i.e., inter-organ communication, which is necessary for this purpose, has been a subject of ongoing research. In particular, it has become clear that metabolism of energy, glucose, lipids, and amino acids is dynamically regulated at the whole-body level mediated by the nervous system, including afferent, central, and efferent nerves. These findings imply that the central nervous system obtains metabolic information from peripheral organs at all times and sends signals selectively to peripheral organs/tissues to maintain metabolic homeostasis, and that the liver plays an important role in sensing and transmitting information on the metabolic status of the body. Furthermore, the utilization of these endogenous mechanisms is expected to lead to the development of novel preventive/curative therapies for metabolic diseases such as diabetes and obesity.(This is a summarized version of the subject matter presented at Symposium 7 presented at the 43rd Annual Meeting of the Japanese Society of Inflammation and Regeneration.).
ABSTRACT
The enhancement of insulin secretion and of the proliferation of pancreatic ß cells are promising therapeutic options for diabetes. Signals from the vagal nerve regulate both processes, yet the effectiveness of stimulating the nerve is unclear, owing to a lack of techniques for doing it so selectively and prolongedly. Here we report two optogenetic methods for vagal-nerve stimulation that led to enhanced glucose-stimulated insulin secretion and to ß cell proliferation in mice expressing choline acetyltransferase-channelrhodopsin 2. One method involves subdiaphragmatic implantation of an optical fibre for the photostimulation of cholinergic neurons expressing a blue-light-sensitive opsin. The other method, which suppressed streptozotocin-induced hyperglycaemia in the mice, involves the selective activation of vagal fibres by placing blue-light-emitting lanthanide microparticles in the pancreatic ducts of opsin-expressing mice, followed by near-infrared illumination. The two methods show that signals from the vagal nerve, especially from nerve fibres innervating the pancreas, are sufficient to regulate insulin secretion and ß cell proliferation.
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Elucidating the mechanism(s) modulating appropriate tissue size is a critical biological issue. Pancreatic ß cells increase during pregnancy via cellular proliferation, but how ß cells promptly decrease to the original amount after parturition remains unclear. Herein, we demonstrate the role and mechanism of macrophage accumulation in this process. In the final stage of pregnancy, HTR1D signaling upregulates murine ß cell CXCL10, thereby promoting macrophage accumulation in pancreatic islets via the CXCL10-CXCR3 axis. Blocking this mechanism by administering an HTR1D antagonist or the CXCR3 antibody and depleting islet macrophages inhibited postpartum ß cell mass reduction. ß cells engulfed by macrophages increased in postpartum islets, but Annexin V administration suppressed this engulfment and the postpartum ß cell mass reduction, indicating the accumulated macrophages to phagocytose ß cells. This mechanism contributes to both maintenance of appropriate ß cell mass and glucose homeostasis promptly adapting to reduced systemic insulin demand after parturition.
Subject(s)
Insulin-Secreting Cells , Islets of Langerhans , Pregnancy , Female , Mice , Animals , Insulin-Secreting Cells/physiology , Parturition , Insulin , Macrophages , PhagocytosisABSTRACT
A 25-year-old man was diagnosed with diabetic ketoacidosis (DKA) at the onset of fulminant type 1 diabetes. After acute-phase DKA treatment including placement of a central venous catheter, a massive deep vein thrombosis (DVT) and pulmonary embolism (PE) were detected on hospital day 15. His protein C (PC) activity and antigen levels were low even 33 days after completing the DKA treatment, indicating partial type I PC deficiency. Severe PC dysfunction, due to overlapping of partial PC deficiency and hyperglycemia-induced PC suppression, concomitant with dehydration and catheter treatment, may have induced the massive DVT with PE. This case suggests that anti-coagulation therapy should be combined with acute-phase DKA treatment in patients with PC deficiency, even those who have been asymptomatic. As patients with partial PC deficiency should perhaps be included among those with severe DVT complications of DKA, venous thrombosis should always be considered as a potential complication of DKA.
Subject(s)
Diabetes Mellitus, Type 1 , Diabetic Ketoacidosis , Protein C Deficiency , Pulmonary Embolism , Venous Thrombosis , Male , Humans , Adult , Diabetes Mellitus, Type 1/complications , Protein C Deficiency/complications , Venous Thrombosis/complications , Pulmonary Embolism/complications , Diabetic Ketoacidosis/complications , Diabetic Ketoacidosis/therapy , Risk FactorsABSTRACT
Cell proliferation processes play pivotal roles in timely adaptation to many biological situations. Herein, we establish a highly sensitive and simple strategy by which time-series showing the proliferation of a targeted cell type can be quantitatively monitored in vivo in the same individuals. We generate mice expressing a secreted type of luciferase only in cells producing Cre under the control of the Ki67 promoter. Crossing these with tissue-specific Cre-expressing mice allows us to monitor the proliferation time course of pancreatic ß-cells, which are few in number and weakly proliferative, by measuring plasma luciferase activity. Physiological time courses, during obesity development, pregnancy and juvenile growth, as well as diurnal variation, of ß-cell proliferation, are clearly detected. Moreover, this strategy can be utilized for highly sensitive ex vivo screening for proliferative factors for targeted cells. Thus, these technologies may contribute to advancements in broad areas of biological and medical research.
Subject(s)
Biomedical Research , Erythrocytes, Abnormal , Female , Pregnancy , Animals , Mice , Acclimatization , Biological Transport , Cell ProliferationABSTRACT
AIMS/INTRODUCTION: To investigate whether the COVID-19 pandemic affected behavioral changes and glycemic control in patients with diabetes and to conduct a survey of telemedicine during the pandemic. MATERIALS AND METHODS: In this retrospective study, a total of 2,348 patients were included from 15 medical facilities. Patients were surveyed about their lifestyle changes and attitudes toward telemedicine. Hemoglobin A1c (HbA1c) levels were compared among before (from June 1 to August 31, 2019) and in the first (from June 1 to August 31, 2020) and in the second (from June 1 to August 31, 2021) year of the pandemic. A survey of physician attitudes toward telemedicine was also conducted. RESULTS: The HbA1c levels were comparable between 2019 (7.27 ± 0.97%), 2020 (7.28 ± 0.92%), and 2021 (7.25 ± 0.94%) without statistical difference between each of those 3 years. Prescriptions for diabetes medications increased during the period. The frequency of eating out was drastically reduced (51.7% in 2019; 30.1% in 2020), and physical activity decreased during the pandemic (48.1% in 2019; 41.4% in 2020; 43.3% in 2021). Both patients and physicians cited increased convenience and reduced risk of infection as their expectations for telemedicine, while the lack of physician-patient interaction and the impossibility of consultation and examination were cited as sources of concern. CONCLUSIONS: Our data suggest that glycemic control did not deteriorate during the COVID-19 pandemic with appropriate intensification of diabetes treatment in patients with diabetes who continued to attend specialized diabetes care facilities, and that patients and physicians shared the same expectations and concerns about telemedicine.
Subject(s)
COVID-19 , Diabetes Mellitus , Telemedicine , Humans , Glycemic Control , Pandemics , Retrospective Studies , COVID-19/epidemiology , Glycated Hemoglobin , Diabetes Mellitus/epidemiology , Diabetes Mellitus/therapyABSTRACT
Accumulating evidence suggests health benefits of ketone bodies, and especially for longevity. However, the precise role of endogenous ketogenesis in mammalian life span, and the safety and efficacy of the long-term exogenous supplementation of ketone bodies remain unclear. In the present study, we show that a deficiency in endogenous ketogenesis, induced by whole-body Hmgcs2 deletion, shortens life span in mice, and that this is prevented by daily ketone body supplementation using a diet containing 1,3-butanediol, a precursor of ß-hydroxybutyrate. Furthermore, feeding the 1,3-butanediol-containing diet from early in life increases midlife mortality in normal mice, but in aged mice it extends life span and prevents the high mortality associated with atherosclerosis in ApoE-deficient mice. By contrast, an ad libitum low-carbohydrate ketogenic diet markedly increases mortality. In conclusion, endogenous ketogenesis affects mammalian survival, and ketone body supplementation may represent a double-edged sword with respect to survival, depending on the method of administration and health status.
Subject(s)
Ketone Bodies , Longevity , Mice , Animals , Butylene Glycols , 3-Hydroxybutyric Acid , MammalsABSTRACT
Crosstalk among organs/tissues is important for regulating systemic metabolism. Here, we demonstrate inter-organ crosstalk between hepatic insulin and hypothalamic leptin actions, which maintains survival during food shortages. In inducible liver insulin receptor knockout mice, body weight is increased with hyperphagia and decreased energy expenditure, accompanied by increased circulating leptin receptor (LepR) and decreased hypothalamic leptin actions. Additional hepatic LepR deficiency reverses these metabolic phenotypes. Thus, decreased hepatic insulin action suppresses hypothalamic leptin action with increased liver-derived soluble LepR. Human hepatic and circulating LepR levels also correlate negatively with hepatic insulin action indices. In mice, food restriction decreases hepatic insulin action and energy expenditure with increased circulating LepR. Hepatic LepR deficiency increases mortality with enhanced energy expenditure during food restriction. The liver translates metabolic cues regarding energy-deficient status, which is reflected by decreased hepatic insulin action, into soluble LepR, thereby suppressing energy dissipation and assuring survival during food shortages.
Subject(s)
Insulin , Leptin , Animals , Mice , Humans , Leptin/metabolism , Insulin/metabolism , Liver/metabolism , Body Weight , Hypothalamus/metabolism , Mice, Knockout , Receptors, Leptin/genetics , Receptors, Leptin/metabolism , Energy Metabolism/geneticsABSTRACT
We experienced a case with insulin allergy which manifested soon after COVID-19 vaccination.
Subject(s)
COVID-19 , Hypersensitivity , Insulins , Humans , BNT162 Vaccine , COVID-19 Vaccines , VaccinationABSTRACT
Insulin like growth factor-1 (IGF-1) plays important roles in metabolic functions, especially in adulthood. Additionally, obese subjects are reportedly predisposed to having low absolute IGF-1 levels. However, the prevalence and clinical characteristics of obese subjects with low IGF-1 levels are unknown. We examined 64 obese subjects with a body mass index (BMI) ≥ 35 kg/m2, with no history of endocrinological disorders, receiving inpatient care. IGF-1 levels were interpreted based on the IGF-1 standard deviation score (SDS) clinically used and standardized by age and sex (low IGF-1 group; ≤ - 2.0 SDS and standard IGF-1 group; - 2.0 < and < + 2.0 SDS). Notably, 26.6% of the subjects had low IGF-1. Body fat mass and percentage, but not BMI, were significantly higher in the low than in the standard IGF-1 group. Furthermore, natural log-transformed high-sensitivity C-reactive protein, and the frequencies of dyslipidemia and hyperuricemia were higher in the low IGF-1 group. Moreover, among the subjects without diabetes, fasting glucose levels were significantly higher in the low IGF-1 group. Stepwise variable selection procedure revealed body fat percentage to be a parameter most strongly associated with low IGF-1. Thus, low IGF-1 levels may be an important marker of adiposity-associated metabolic disorders in obese patients.
Subject(s)
Insulin-Like Growth Factor I , Metabolic Diseases , Humans , Adult , Retrospective Studies , Japan/epidemiology , Metabolic Diseases/complications , Metabolic Diseases/epidemiology , Comorbidity , Obesity/complications , Obesity/epidemiologyABSTRACT
OBJECTIVE: This study was performed to investigate the association of hypertension subtypes with glucose metabolism among the Japanese general population. METHODS: The study involved 646 residents (mean age: 62.4âyears) without treatment for hypertension or a history of diabetes from Ohasama, a rural Japanese community, who underwent an oral glucose tolerance test. Hypertension subtypes [normotension, isolated systolic hypertension (ISH), isolated diastolic hypertension (IDH), and systolic and diastolic hypertension (SDH)] were defined on the basis of home and office SBP and DBP (HBP and OBP, respectively). The estimated means of blood glucose related indices among the groups were compared by analysis of covariance adjusted for possible confounding factors. RESULTS: Blood glucose related indices were not different among the morning HBP-defined hypertension subtypes. Participants with evening HBP-defined ISH had a significantly higher estimated mean BG at 120âmin, higher homeostasis model assessment-insulin resistance (HOMA-IR) and lower Matsuda-DeFronzo index than participants with NT (all Pâ<â0.021). Participants with OBP-defined SDH had a significantly higher estimated mean fasting blood glucose; blood glucose at 30, 60 and 120âmin; and HOMA-IR and a lower Matsuda-DeFronzo index than participants with NT (all Pâ<â0.0025). CONCLUSION: The blood glucose related indices were different among hypertension subtypes. Participants with evening HBP-defined ISH and OBP-defined SDH had higher blood glucose levels and insulin resistance than participants with correspondingly defined normotension, while those with morning HBP did not. These findings suggest the importance of measuring evening HBP and office blood pressure for early detection of coexisting hypertension and diabetes.
Subject(s)
Hypertension , Insulin Resistance , Blood Glucose , Glucose , Humans , Middle Aged , SystoleABSTRACT
AIMS/INTRODUCTION: Whether basal ß-cell proliferation during adulthood is involved in maintaining sufficient ß-cell mass, and if so, the molecular mechanism(s) underlying basal ß-cell proliferation remain unclear. FoxM1 is a critical transcription factor which is known to play roles in 'adaptive' ß-cell proliferation, which facilitates rapid increases in ß-cell mass in response to increased insulin demands. Therefore, herein we focused on the roles of ß-cell FoxM1 in 'basal' ß-cell proliferation under normal conditions and in the maintenance of sufficient ß-cell mass as well as glucose homeostasis during adulthood. MATERIALS AND METHODS: FoxM1 deficiency was induced specifically in ß-cells of 8-week-old mice, followed by analyzing its short- (2 weeks) and long- (10 months) term effects on ß-cell proliferation, ß-cell mass, and glucose tolerance. RESULTS: FoxM1 deficiency suppressed ß-cell proliferation at both ages, indicating critical roles of FoxM1 in basal ß-cell proliferation throughout adulthood. While short-term FoxM1 deficiency affected neither ß-cell mass nor glucose tolerance, long-term FoxM1 deficiency suppressed ß-cell mass increases with impaired insulin secretion, thereby worsening glucose tolerance. In contrast, the insulin secretory function was not impaired in islets isolated from mice subjected to long-term ß-cell FoxM1 deficiency. Therefore, ß-cell mass reduction is the primary cause of impaired insulin secretion and deterioration of glucose tolerance due to long-term ß-cell FoxM1 deficiency. CONCLUSIONS: Basal low-level proliferation of ß-cells during adulthood is important for maintaining sufficient ß-cell mass and good glucose tolerance and ß-cell FoxM1 underlies this mechanism. Preserving ß-cell FoxM1 activity may prevent the impairment of glucose tolerance with advancing age.