Insulin resistance and endothelial dysfunction in smokers: effects of vitamin C

2000 ◽  
Vol 279 (3) ◽  
pp. H1172-H1178 ◽  
Author(s):  
Nobutaka Hirai ◽  
Hiroaki Kawano ◽  
Osamu Hirashima ◽  
Takeshi Motoyama ◽  
Yasushi Moriyama ◽  
...  
Keyword(s):  
Risk Factors ◽  
Insulin Resistance ◽  
Insulin Sensitivity ◽  
Endothelial Dysfunction ◽  
Vitamin C ◽  
Glucose Tolerance ◽  
Endothelial Function ◽  
Thiobarbituric Acid ◽  
Normal Glucose Tolerance ◽  
Normal Glucose

Cigarette smoking impairs endothelial function and is one of the major risk factors for atherosclerosis and coronary heart disease. Insulin resistance is associated with major risk factors for atherosclerosis. We examined the effects of vitamin C on insulin sensitivity and endothelial function by measuring steady-state plasma glucose (SSPG) and flow-mediated dilation (FMD) of the brachial artery. We studied 16 current smokers with normal glucose tolerance, 15 nonsmokers with impaired glucose tolerance (IGT), and 17 nonsmokers with normal glucose tolerance as controls. Both SSPG and FMD were blunted in smokers and nonsmokers with IGT compared with controls. In smokers, vitamin C decreased SSPG ( P < 0.01 by ANOVA) with decreasing plasma thiobarbituric acid-reactive substances (TBARS) ( P < 0.05 by ANOVA) and improved FMD ( P < 0.05 by ANOVA). Furthermore, vitamin C improved both SSPG ( P < 0.005 by ANOVA) and FMD ( P < 0.05 by ANOVA) in nonsmokers with IGT. SSPG, FMD, or TBARS in controls did not change after vitamin C infusion. There was a significant correlation between SSPG and FMD both in smokers and nonsmokers with IGT, whereas no correlation was observed in controls. In conclusion, both insulin sensitivity and endothelial function were impaired in smokers and nonsmokers with IGT and were improved by vitamin C. Thus increased reactive oxygen species play an important role in the pathogenesis of insulin resistance as well as endothelial dysfunction in smokers and nonsmokers with IGT.

scholarly journals In middle-aged siblings of patients with type 2 diabetes mellitus normal glucose tolerance is associated with insulin resistance and with increased insulin secretion. The SPIDER study

2000 ◽  
pp. 681-686 ◽  
Author(s):  
AE Pontiroli ◽  
LD Monti ◽  
S Costa ◽  
PE Sandoli ◽  
A Pizzini ◽  
...  
Keyword(s):  
Diabetes Mellitus ◽  
Insulin Resistance ◽  
Type 2 Diabetes ◽  
Insulin Sensitivity ◽  
Glucose Tolerance ◽  
Normal Glucose Tolerance ◽  
C Peptide ◽  
Type 2 Dm ◽  
Normal Glucose

OBJECTIVES: To evaluate the frequency of impaired glucose tolerance (IGT) and of Type 2 diabetes mellitus (Type 2 DM) in siblings of patients with Type 2 DM, and to assess insulin release and insulin sensitivity in siblings with normal glucose tolerance (NGT), compared with NGT spouses of probands without family history of Type 2 DM. DESIGN AND METHODS: We evaluated 87 families including 103 Type 2 DM patients (87 probands), and we carried out an oral glucose tolerance test (OGTT) in 130 siblings and in 60 spouses. Among NGT subjects, 12 siblings and 16 spouses underwent a low-dose insulin-glucose infusion test (LDIGIT) to evaluate C-peptide release and insulin sensitivity. RESULTS: After the OGTT, 24 siblings were classified as having Type 2 DM, 31 as IGT, and only 14 spouses as IGT (P=0.0012 vs siblings). NGT siblings (n=75) showed higher insulin levels at 120 min than NGT spouses (n=46) at OGTT, in spite of identical blood glucose levels; at LDIGIT, NGT siblings secreted more C-peptide and showed a lower insulin sensitivity than NGT spouses. CONCLUSIONS: These data indicate that middle-aged siblings of probands with Type 2 DM have a high frequency of IGT and Type 2 DM, and that NGT siblings have increased insulin resistance and increased insulin secretion when compared with adequate controls.

Insulin resistance and cardiovascular risk factors in women with PCOS who have normal glucose tolerance test

2012 ◽  
Vol 29 (2) ◽  
pp. 148-151 ◽  
Author(s):  
Ismail Cem Yildir ◽  
Faruk Kutluturk ◽  
Turker Tasliyurt ◽  
Berna Murat Yelken ◽  
Berat Acu ◽  
...  
Keyword(s):  
Risk Factors ◽  
Insulin Resistance ◽  
Cardiovascular Risk ◽  
Glucose Tolerance ◽  
Cardiovascular Risk Factors ◽  
Glucose Tolerance Test ◽  
Tolerance Test ◽  
Normal Glucose Tolerance ◽  
Normal Glucose

scholarly journals Assessment of Insulin Resistance in Subjects with Normal Glucose Tolerance, Hyperinsulinemia with Normal Blood Glucose Tolerance, Impaired Glucose Tolerance, and Newly Diagnosed Type 2 Diabetes (Prediabetes Insulin Resistance Research)

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Guang Yang ◽  
Chunlin Li ◽  
Yanping Gong ◽  
Fusheng Fang ◽  
Hui Tian ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Type 2 Diabetes ◽  
Insulin Sensitivity ◽  
Glucose Tolerance ◽  
Normal Glucose Tolerance ◽  
Newly Diagnosed ◽  
Factors Influencing ◽  
Sensitivity Indices ◽  
Normal Glucose

Aim.To evaluate the differences in insulin resistance (IR) among subjects with normal glucose tolerance (NGT), hyperinsulinemia with NGT (HINS), impaired glucose tolerance (IGT), and newly diagnosed type 2 diabetes mellitus (T2DM).Methods.5 NGT, 25 HINS, 25 IGT, and 25 T2DM subjects participated in this research. The hyperinsulinemic-euglycemic clamp technique (HECT) was performed in all of them to evaluate IR levels. The relative factors influencing IR were evaluated. The simple insulin sensitivity indices were calculated, and the correlation between each index and the M value was analyzed.Results.TheMvalues of NGT, HINS, IGT, and T2DM groups were 11.88 ± 2.93 mg·kg−1·min−1, 6.23 ± 1.73 mg·kg−1·min−1, 6.37 ± 2.12 mg·kg−1·min−1, and 6.19 ± 1.89 mg·kg−1·min−1, respectively.Mvalues in HINS, IGT, and T2DM groups were lower than those in the NGT group (P=0.005); however, the differences among the HINS, IGT, and T2DM groups were not statistically significant (P=0.835). The independent factors influencing theMvalue were waistline and fasting insulin level (FINS). The simple insulin sensitivity indices, especially Matsuda and Gutt index, were significantly associated with theMvalue (P<0.01).Conclusion.IR existed in the HINS, IGT, and T2DM groups, and IR levels were consistent in the three groups. The independent factors influencing IR were waistline and FINS.

scholarly journals Dissociation Between Insulin Resistance and Abnormalities in Lipoprotein Particle Concentrations and Sizes in Normal-Weight Chinese Adults

2021 ◽  
Vol 8 ◽  
Author(s):  
Kaare Tranæs ◽  
Cherlyn Ding ◽  
Yu Chung Chooi ◽  
Zhiling Chan ◽  
John Choo ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Insulin Sensitivity ◽  
Glucose Tolerance ◽  
Lipid Profile ◽  
Normal Glucose Tolerance ◽  
Proton Nuclear Magnetic Resonance ◽  
Lipoprotein Subclass ◽  
Insulin Resistant ◽  
Lipoprotein Particle ◽  
Normal Glucose

Insulin resistance in obesity coincides with abnormalities in lipid profile and lipoprotein subclass distribution and size even before abnormalities in glucose homeostasis manifest. We aimed to assess this relationship in the absence of obesity. Insulin sensitivity (3-h intravenous glucose tolerance test and minimal modeling) and lipoprotein particle concentrations and sizes (proton nuclear magnetic resonance spectroscopy) were evaluated in 15 insulin-resistant and 15 insulin-sensitive lean Asians of Chinese descent with normal glucose tolerance, matched on age, sex, and body mass index. Despite a ~50% lower insulin sensitivity index (Si) in insulin-resistant than in insulin-sensitive subjects, which was accompanied by significantly greater acute insulin response to glucose (AIRg) and fasting insulin concentration but not different fasting glucose concentration, there were no significant differences between groups in the blood lipid profile (p ≥ 0.44) or the lipoprotein subclass concentrations (p ≥ 0.30) and particle sizes (p ≥ 0.43). We conclude that, contrary to observations in subjects with obesity, insulin resistance is not accompanied by unfavorable changes in the plasma lipid profile and lipoprotein particle concentrations and sizes in lean Asians with normal glucose tolerance. Therefore, insulin resistance at the level of glucose metabolism is mechanistically or temporally dissociated from lipid and lipoprotein metabolism.Trial Registration:clinicaltrials.gov, NCT03264001.

scholarly journals Plasma DPP4 Activities Are Associated With Osteoporosis in Postmenopausal Women With Normal Glucose Tolerance

2015 ◽  
Vol 100 (10) ◽  
pp. 3862-3870 ◽  
Author(s):  
Tianpeng Zheng ◽  
Liuxue Yang ◽  
Yihong Liu ◽  
Hongbo Liu ◽  
Jian Yu ◽  
...  
Keyword(s):  
Risk Factors ◽  
Insulin Resistance ◽  
Glucose Tolerance ◽  
Total Cholesterol ◽  
Postmenopausal Women ◽  
Type I Collagen ◽  
Normal Glucose Tolerance ◽  
Type I ◽  
Normal Glucose ◽  
Hs Crp

Context: Inflammation, insulin resistance, dyslipidemia, and glucagon-like peptide-1 (GLP-1) are risk factors for osteoporosis. Dipeptidyl peptidase-4 (DPP4) is a newly identified adipokine related to these risk factors. Objective: To investigate the association between plasma DPP4 activities and osteoporosis. Design, Setting, and Patients: This was a cross-sectional study conducted in Guilin, China. A total of 744 postmenopausal women with normal glucose tolerance were studied. Main Outcome Measures: Plasma DPP4 activity, inflammatory markers, blood lipids, homeostatic model assessment of insulin resistance (HOMA-IR), active GLP-1, bone turnover markers, and bone mineral density (BMD) were measured in all participants. Results: Participants in the highest quartile of DPP4 activity had higher triglyceride, total cholesterol, HOMA-IR, IL-6, high-sensitivity C-reactive protein (hs-CRP), C-terminal telopeptide of type I collagen, and osteocalcin and lower BMD (lumbar spine and femoral neck) and active GLP-1 compared with participants in the lowest quartile (P &lt; .05). DPP4 activities were associated positively with triglyceride, total cholesterol, HOMA-IR, IL-6, hs-CRP, C-terminal telopeptide of type I collagen, and osteocalcin and negatively with active GLP-1 and BMD (P &lt; .05). In the highest DPP4 quartile, osteoporosis risk was significantly higher (odds ratio, 3.01; 95% confidence interval, 1.66–5.43) than in the lowest quartile after adjustment for potential confounders. The risk for osteoporosis increased more with higher levels of DPP4 activity, HOMA-IR, IL-6, and hs-CRP (P &lt; .05), but not with higher levels of triglyceride and total cholesterol or lower levels of active GLP-1. Conclusions: This study shows that increased DPP4 activities are independently associated with osteoporosis. The mechanisms may be partly explained by the effect of DPP4 on inflammation and insulin resistance.

Sign in / Sign up

Export Citation Format

Share Document