Post-challenge hyperinsulinaemia rather than hyperglycaemia is associated with the severity of coronary artery disease in patients without a previous diagnosis of diabetes mellitus

Islet function changes of post-glucose-challenge relate closely to 15 years mortality of elderly men with a history of hyperglycemia

Aims

We aimed to investigate the relationship between islet function changes during a glucose challenge and 15-year mortality in elderly men.

Methods

Elderly men who did the oral glucose tolerance test in 2005 owing to an abnormal glucose history without diabetes were included. Changes in insulin resistance and secretion were evaluated using the homeostasis model assessment (HOMA) of fast, post-load, and ratios. Comparisons between the dead and the survival groups were analyzed using the Student's t-test (continuous variables) or χ2 test (Categorical variables). Single-factor logistic regression was used to identify the possible affecting factors. Multifactorial logistic regression was used to identify the independent risk factors in total population and in the subgroups. ROC curve was used to assess the predictive ability of risk factor and to determine the cut-off value.

Results

Of the 220 elderly men, 67 died according to 15-year retrospection. Age (OR = 1.243, P = 0.000), diastolic pressure (OR = 0.958, P = 0.027), and HOMA-IR (2 h/0 h) (OR = 1.040, P = 0.010) were independent risk factors for 15-year mortality. Subgroup analysis showed that HOMA-IR (2 h/0 h) was an obvious risk factor, especially for normal glucose tolerance (OR = 1.060, P = 0.030), age 60-70 years (OR = 1.068, P = 0.005), and hypertension (OR = 1.048, P = 0.013); HOMA-β (2 h/0 h) showed some protective effects in the impaired glucose regulation subgroup (OR = 0.779, P = 0.057). HOMA-IR (2 h/0 h) cut-off value was 15.

Conclusions

HOMA-IR (2 h/0 h) higher than 15 was an independent risk factor for 15-year mortality in elderly men with hyperglycemia history.

Diurnal glycemic fluctuation is associated with severity of coronary artery disease in prediabetic patients: Possible role of nitrotyrosine and glyceraldehyde-derived advanced glycation end products

BACKGROUND

Glucose fluctuation (GF) is a risk factor for coronary artery disease (CAD). However, it remains unknown whether specific indices of GF are risk factors for CAD. Therefore, we evaluated the relationship between GF, as determined by a continuous glucose monitoring system (CGMS) or the glucose level at 2h after a 75-g oral glucose tolerance test (75g OGTT 120), and the severity of CAD in prediabetic patients. We also evaluated whether nitrotyrosine (NT) and glyceraldehyde-derived advanced glycation end-products (Glycer-AGE) were induced by GF.

METHODS

Twenty-eight prediabetic patients underwent coronary angiography (CAG), and the Gensini score and the SYNTAX score were evaluated as the severity of CAD, while the mean amplitude of glycemic excursions (MAGE) by CGMS and 75g OGTT 120 were evaluated. Serum NT and Glycer-AGE were measured.

RESULTS

The MAGE was closely associated with the Gensini score (r=0.742, p<0.001) and the SYNTAX score (r=0.776, p<0.001), respectively. The 75g OGTT 120 was not associated with the Gensini score (r=0.36, p=0.06), but it was significantly associated with the SYNTAX score (r=0.413, p=0.036). Multiple linear regression analysis showed that the MAGE was the only independent determinant for the severity of CAD. The levels of NT and Glycer-AGE were significantly higher in the high MAGE group than in the low MAGE group.

CONCLUSIONS

Diurnal GF is associated with the severity of CAD, even in prediabetic patients. GF, NT, and Glycer-AGE may play a pathological role in the progression of CAD.

Postchallenge responses of nitrotyrosine and TNF-alpha during 75-g oral glucose tolerance test are associated with the presence of coronary artery diseases in patients with prediabetes

BACKGROUND

Meta-analysis has demonstrated an exponential relationship between 2-hr postchallenge hyperglycemia and coronary artery disease (CAD). Pulsatile hyperglycemia can acutely increase proinflammatory cytokines by oxidative stress. We hypothesized that postchallenge proinflammatory and nitrosative responses after 75 g oral glucose tolerance tests (75 g-OGTT) might be associated with CAD in patients without previously recognized type 2 diabetes mellitus (T2DM).

METHODS

Serial changes of plasma glucose (PG), tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6) and nitrotyrosine levels were analyzed during 75 g-OGTT in 120 patients (81 male; age 62 ± 11 years) before coronary angiography. Patients were classified as normal (NGT; 42%), impaired (IGT; 34%) and diabetic (T2DM; 24%) glucose tolerance by 75 g-OGTT.

RESULTS

Postchallenge hyperglycemia elicited TNF-α, IL-6 and nitrotyrosine levels time-dependently, and 2-hr median levels of TNF-α (7.1 versus 6.4 pg/ml; P < 0.05) and nitrotyrosine (1.01 versus 0.83 μmol/l; P < 0.05), but not IL-6 or PG, were significantly higher in patients with CAD in either IGT or T2DM groups. After adjusting risk factors and glucose tolerance status, 2-hr nitrotyrosine in highest quartiles (OR: 3.1, P < 0.05) remained an independent predictor of CAD by logistic regression analysis.

CONCLUSIONS

These results highlight postchallenge proinflammatory and nitrosative responses by 75 g-OGTT, rather than hyperglycemia per se, are associated with CAD in patients without previous recognized diabetes.

Effects of voglibose and nateglinide on glycemic status and coronary atherosclerosis in early-stage diabetic patients

BACKGROUND

Postprandial hyperglycemia and hyperinsulinemia have been considered as important determinants for the development of atherosclerosis. However, it remains to be elucidated whether correction of the postprandial glycemic status prevents atherosclerotic changes.

METHODS AND RESULTS

The DIANA (DIAbetes and diffuse coronary NArrowing) study is a prospective randomized open-label multicenter trial. The 302 patients with coronary artery disease (CAD), impaired glucose tolerance/diabetes mellitus (DM) pattern according to 75-g oral glucose tolerance test and HbA(1c) <6.9% were randomly assigned to life-style intervention (n=101), voglibose (0.9 mg/day, n=100) or nateglinide treatment (180 mg/day, n=101). We compared 1-year coronary atherosclerotic changes evaluated by quantitative coronary arteriography. Although voglibose significantly increased the number of patients with normal glucose tolerance at 1 year, there were no significant differences in coronary atherosclerotic changes at 1 year. However, overall, less atheroma progression was observed in patients in whom glycemic status was improved at 1 year (%change in total lesion length: 3.5% vs. 26.2%, P<0.01, %change in averaged lesion length: 0.7% vs. 18.6%, P=0.02).

CONCLUSIONS

Although coronary atherosclerotic changes were similar for voglibose and nateglinide, an improvement in glycemic status at 1 year was associated with less atheroma progression regardless of the treatment. Our findings underscore the management of glycemic abnormality to prevent coronary atherosclerotic changes in Japanese early-stage DM patients with CAD.

Comparison of three-year clinical outcomes after sirolimus-eluting stent implantation among insulin-treated diabetic, non-insulin-treated diabetic, and non-diabetic patients from j-Cypher registry

The purpose of the present study was to evaluate the 3-year clinical outcomes after percutaneous coronary intervention with sirolimus-eluting stents in patients with insulin-treated diabetes mellitus (DM-insulin) and those with non-insulin-treated DM (DM-non-insulin) compared to patients without DM. Of 10,778 consecutive patients treated exclusively with sirolimus-eluting stents in the j-Cypher registry, we identified 996 patients with DM-insulin, 3,404 with DM-non-insulin, and 6,378 without DM. Compared to the non-DM group, the adjusted risk of a serious cardiovascular event (composite of all-cause death, myocardial infarction, and stroke) was significantly greater in the DM-insulin group (hazard ratio 1.12, 95% confidence interval [CI] 1.03 to 1.23; p = 0.01), but not in the DM-non-insulin group (hazard ratio 1.02, 95% CI 0.96 to 1.09; p = 0.47). The adjusted risk of target lesion revascularization was significantly greater in both the DM-insulin group (odds ratio 1.52, 95% CI 1.19 to 1.92; p = 0.0006) and the DM-non-insulin group (odds ratio 1.24, 95% CI 1.05 to 1.45; p = 0.009). In conclusion, a diabetes-associated excess risk of target lesion revascularization was found, regardless of insulin use in this large, real-world study of Japanese patients with sirolimus-eluting stent implantation. However, regarding serious cardiovascular events, an excess risk was seen only in the DM-insulin group. The risk of serious cardiovascular events was similar between the DM-non-insulin and non-DM groups.

The Relationship between Glucose Tolerance and Severity of Coronary Artery Disease Using the Gensini Score

Consecutive patients (n = 235) with coronary ischemia were studied; 69 patients (29%) had diabetes. An oral glucose tolerance test (OGTT) was administered to the 166 patients without diabetes; 76 (46%) had normal glucose tolerance (group I = NGT), 68 (41%) had impaired glucose tolerance ([IGT] group II = IGT), and 22 (13%) had diabetic glucose tolerance (DGT). The DGT patients were added to the known diabetics forming (Group III; n = 91). Multivessel disease was significantly more prevalent in group III; 30 patients (43%) in group I, 32 patients (51%) in group II, and 57 patients (69%) in group III ( P = .002). Gensini scores were 43.20 ± 24.92 in group I, 54.22 ± 42.61 in group II, and 60.59 ± 38.21 in group III. ( P = .037) The severity of coronary artery disease is related to abnormal glucose tolerance. Patients with IGT could be neglected in terms of interventions focused to improve risk factors.

Dysregulation of glucose, insulin, triglyceride, blood pressure, and oxidative stress after an oral glucose tolerance test in men with abdominal obesity

Postprandial metabolic dysregulation plays a role in the development of atherosclerosis. Visceral fat accumulation is an important component of various metabolic disorders including glucose intolerance, dyslipidemia, and hypertension, which correlate with atherosclerotic cardiovascular disease. The aim of the present study was to compare the postprandial response of various metabolic parameters, blood pressure, adiponectin, and oxidative stress to 75-g oral glucose tolerance test (OGTT) in men with (n = 23) and without (n = 7) abdominal obesity based on waist circumference (WC) cutoff value of 85 cm (based on the Japanese criteria for the metabolic syndrome). The cross-sectional prospective study included 30 male subjects who were on no medications and newly diagnosed with mild hypertension and/or dyslipidemia. The percentage change in each parameter ([each parameter at 120 minutes after an OGTT - that before an OGTT]/that before an OGTT x 100) was calculated. The percentage systolic blood pressure, percentage diastolic blood pressure, and percentage triglyceride were -6.3% +/- 3.5%, -9.4% +/- 3.0%, and -10.2% +/- 2.1%, respectively, in the WC less than 85 group (vs baseline: P = .10, P < .01, and P < .001) and 2.0% +/- 1.7%, 0.9% +/- 2.4%, and 2.8% +/- 3.3%, respectively, in the WC at least 85 group (vs WC <85 group: P < .05, each). However, there were no significant differences in percentage total cholesterol and percentage high-density lipoprotein cholesterol between the 2 groups. The percentage thiobarbituric acid-reacting substances tended to be lower in the WC less than 85 group (vs baseline: P = .07), but not in the WC at least 85 group, albeit statistically insignificant (WC <85 vs >/=85 group: P = .057). The maximum carotid intima-media thickness was larger in the WC at least 85 group than the WC less than 85 group (P < .05). Evaluation of postprandial changes in obesity-related parameters may be important in preventing atherosclerotic diseases.

Determination of reference values for elevated fasting and random insulin levels and their associations with metabolic risk factors among rural Pakistanis from Sindh Province

AIM

To assess insulin levels and their association with metabolic risk factors (family history of diabetes, abnormal glucose tolerance, hypertension, overweight and android obesity) among a representative group of Pakistan.

METHODS

The study data was taken from the database of a population-based survey conducted in Sindh Province, Pakistan, in 1994 to assess the prevalence of diabetes mellitus and impaired glucose tolerance (IGT). Through stratified random sampling; oral glucose tolerance tests were performed in 967 adults; every fifth sample was estimated for fasting and random (2-hour post-75 gm glucose load) insulin levels. The total number of metabolic risk factors was counted for each subject, and their association with insulin levels studied.

RESULTS

Of the 130 subjects, 56.1% were females and 95.4% were Sindhi. The mean age of males and females was 43.84 and 40.61 years, respectively. Family history for diabetes and frequency of overweight had significant positive associations with both fasting and random insulin levels (P < 0.05). Association between hypertension and insulin levels was significant only for random insulin levels, and between android obesity, abnormal glucose tolerance, or male gender and insulin levels only for fasting insulin levels (P < 0.05). Metabolic risk factors had significant positive associations with both fasting (r = 0.351 P = 0.000) as well as random insulin levels (r = 0.364 P = 0.000).

CONCLUSION

This paper provides baseline pioneering information applicable to the Pakistani population. Furthermore, the observations made in this study about differences in association of fasting or random insulin levels with various metabolic risk factors highlight the possibility of using either of them for risk assessment. This finding needs to be assessed in a larger and nationally representative sample.

Insulin response to oral glucose load is associated with coronary artery disease in subjects with normal glucose tolerance

AIM

The critical role of hyperinsulinemia, independent of hyperglycemia, in the pathogenesis of atherosclerosis has not been fully determined. We investigated the association between secretion patterns of insulin after oral glucose load and the severity of coronary artery disease (CAD) in patients with normal glucose tolerance (NGT).

METHODS

We enrolled 116 subjects with NGT from 243 patients who had undergone coronary angiography and a standard 75-g oral glucose tolerance test. The patients were divided into 0-vessel, single-vessel and multi-vessel disease groups on the basis of the severity of CAD.

RESULTS

The 2-h insulin levels in the multi-vessel disease group (p=0.005) and the single-vessel disease group (p<0.05) were significantly higher than those in the 0-vessel disease group. Multivariate analysis revealed that the levels of 2-h insulin were an independent variable for the presence of CAD (p=0.02) after adjustment for gender and the presence of each criterion of metabolic syndrome using the definition of the International Diabetes Federation.

CONCLUSION

A slight but significant increase in prolonged insulin secretion, which is associated with the early stage of insulin resistance, in subjects with NGT, may play an important role in the pathogenesis of atherosclerosis.

Impaired fasting glucose and the prevalence and severity of angiographic coronary artery disease in high-risk Chinese patients

We assessed the relation between different fasting plasma glucose (FPG) levels of 5.6 to 6.9 mmol/L and the prevalence and severity of angiographic coronary artery disease (CAD) in high-risk Chinese patients. Among 512 subjects who were to undergo coronary angiography for the confirmation of suspected myocardial ischemia, 409 subjects were enrolled and categorized into 3 groups based on FPG levels: (1) </=5.5 mmol/L, (2) 5.6 to 6.0 mmol/L, and (3) 6.1 to 6.9 mmol/L. Each of these groups was further divided into subgroups by sex; the second and third groups were combined as an additional group according to the 2003 definition of impaired fasting glucose (FPG at 5.6-6.9 mmol/L). We analyzed the coronary artery stenosis score, the prevalence of angiographic CAD, and the percentage of stenosis in the 3 main arteries among the groups and examined the risk factors for angiographic CAD prevalence by logistic regression analysis. A higher correlation was observed between angiographic CAD prevalence and FPG levels of 6.1 to 6.9 mmol/L as compared with FPG levels </=5.5 mmol/L (adjusted odds ratio [OR], 2.67; 95% confidence interval [CI], 1.72-4.10; P = .011). The FPG levels of 5.6 to 6.9 mmol/L (adjusted OR, 2.57; 95% CI, 1.65-4.02; P < .001) and 5.6 to 6.0 mmol/L (adjusted OR, 2.33; 95% CI, 1.58-3.49; P = .008) were modestly correlated with angiographic CAD prevalence. The angiographic CAD prevalence, coronary artery stenosis score, and the percentage of stenosis in the left anterior descending branch increased corresponding to increasing FPG levels from </=5.5 mmol/L to 5.6 to 6.0 mmol/L to 6.1 to 6.9 mmol/L. We concluded that FPG levels of 5.6 to 6.9 mmol/L as well as of 6.1 to 6.9 mmol/L may be an independent risk factor for angiographic CAD; furthermore, there was a progressive and graded relation between FPG levels of 5.6 to 6.9 mmol/L and angiographic CAD prevalence and severity in high-risk Chinese patients.

Insulin resistance as predictor of the angiographic severity and extent of coronary artery disease

BACKGROUND

Insulin resistance (IR) is frequently observed in patients with coronary artery disease (CAD). Aim. To examine the association between IR and severity and extent of CAD.

METHODS

Quantitative coronary angiography (QCA) was used to assess coronary atherosclerosis in 107 patients with clinically suspected CAD. QCA-derived indexes reflecting CAD severity, extent, and overall atheroma burden were calculated for the entire coronary tree, and separately for different coronary segments. IR was quantified using the homeostasis model assessment insulin resistance index (HOMA IR). Nondiabetic subjects (n = 83) were divided into group 1 (n = 41) with HOMA IR <1.8 (the median value), and group 2 (n = 42) with HOMA IR >or=1.8. Group 3 comprised diabetic subjects (n = 24).

RESULTS

Global age- and gender-adjusted indexes for severity (P = 0.007), extent (P = 0.038), and atheroma burden (P = 0.035) of CAD were higher in group 2 than in group 1. Similarly, the global severity (P = 0.027), extent (P = 0.090), and global atheroma burden (P = 0.024) indexes were higher in group 3 compared with group 1. IR was correlated with quantitative angiographic indexes for distal segments only, but not for proximal or mid segments of coronary vessels.

CONCLUSIONS

Patients with more severe degree of IR have a more severe, extensive, and distal type of CAD than patients with lower degree of IR.

Impact of Abnormal Glucose Tolerance, Hypertension and Other Risk Factors on Coronary Artery Disease

BACKGROUND

The degree to which abnormal glucose tolerance contributes to the development of coronary artery disease (CAD) has not been clarified in Japanese. The relationship between abnormal glucose tolerance and severity of coronary artery stenosis, as well as the contributions of hypertension, diabetes and other risk factors for CAD to recurrence of the disease, were investigated in the present study.

METHODS AND RESULTS

The subjects were 474 consecutive patients (mean age: 63.8+/-11.3 years) with suspected CAD who were admitted to Sapporo Medical University Hospital during April 1, 1997 to March 31, 2004. The coronary index and stenosis score were higher in subjects with diabetes mellitus (DM) and in subjects with impaired fasting glucose (IFG) and impaired glucose tolerance (IGT) than in subjects with normal glucose tolerance (NGT). Ischemic episodes recurred during the observation period (mean 2.5 years) in 61 of 341 patients diagnosed as having CAD. In the follow-up subjects, systolic blood pressure (SBP) was significantly higher in the recurrence group than in the non-recurrence group, and SBP was a significant variable in logistic regression analysis after adjustment for age, gender, hemoglobin A1c, total cholesterol, body mass index, smoking history, family history and stenosis score. The relative risk of recurrence became 1.7-fold higher with a rise in SBP of 10 mmHg (95% confidence interval: 1.252-2.250). Analysis of the relationship between glucose tolerance and recurrence showed that the rate of recurrence was higher in patients with IFG+IGT+DM than in those with NGT.

CONCLUSIONS

CAD progresses not only in patients with DM but also in those with IGT. The rate of recurrence of ischemic episodes increases in individuals with IGT or DM, and suggesting that hypertension is a risk factor for recurrence of ischemic episodes. Management of glucose tolerance and blood pressure is therefore important for prevention of CAD in Japanese.

Global myocardial perfusion and diastolic function are impaired to a similar extent in patients with type 2 diabetes mellitus and in patients with coronary artery disease--evaluation by contrast echocardiography and pulsed tissue Doppler

AIMS/HYPOTHESIS

Using modern echocardiography, we quantified the extent of global myocardial function and perfusion abnormalities in patients with type 2 diabetes and compared this with the hypothetically similar extent of impairments in patients with coronary artery disease (CAD).

SUBJECTS AND METHODS

This case-control study (66 patients) compared four age-matched groups: control, type 2 diabetic, CAD, and diabetic subjects with CAD (DCAD) and left ventricular ejection fraction >50%. CAD patients had 1-2 vessel disease. Diastolic and systolic myocardial velocities were assessed with pulsed tissue Doppler. Global myocardial perfusion was assessed with contrast echocardiography as indices of capillary blood volume and myocardial blood flow at maximal vasodilatation. In CAD and DCAD patients, functional and perfusion parameters were additionally assessed in the territory with a normal coronary angiogram reading, providing a model for comparison with the global data from control and diabetic patients.

RESULTS

Comparing diabetic with control subjects, myocardial velocity at early diastole was impaired (8.8+/-1.8 vs 10.1+/-1.7 cm/s; p=0.02) and correlated inversely with age, HbA(1c) and pulse pressure (R (2)=0.761). Capillary blood volume (16.6+/-5.0 vs 24.4+/-4.9%) and blood flow (56+/-35 vs 114+/-40) were decreased (p=0.001). In CAD patients, myocardial velocity at early diastole was similarly decreased (p=0.02). CAD and DCAD patients were receiving more cardiovascular preventive therapy for the same extent of impaired global perfusion as in the less extensively treated diabetes group without CAD (p<0.002), but had superior perfusion of the 'normal' coronary territory than that group (p<0.05).

CONCLUSIONS/INTERPRETATION

In patients with diabetes, global diastolic function and myocardial capillary blood volume and blood flow are impaired to the same extent as in patients with CAD. These impairments could form the basis of new therapeutic concepts.

Inverse Relationship Between Adiponectin Levels and Subclinical Carotid Atherosclerosis in Patients Undergoing Coronary Artery Bypass Grafting

The purpose of this study was to examine the relation between adiponectin levels and subclinical carotid atherosclerosis in patients undergoing coronary artery bypass grafting (CABG). Serum concentrations of adiponectin and carotid intima/media thickness (IMT) were measured in 84 consecutive patients who underwent CABG. Carotid IMT both at the common carotid artery and carotid bulb level was correlated negatively and significantly (r = -0.581 and r = -0.415, respectively, P < 0.01) with the serum concentrations of adiponectin. Linear regression modeling identified adiponectin as the strongest predictive variable for carotid IMT both at the common carotid artery and carotid bulb level (P < 0.001). Stepwise regression analyses also showed that adiponectin was the strongest independent determinant of the carotid IMT both at the common carotid artery and the carotid bulb level (F = 20.215 and F = 19.565, respectively, P < 0.001). The mean number of diseased coronary arteries, mean number of distal anastomoses, cardiopulmonary bypass time, and aortic cross-clamping time did not significantly correlate with the serum concentrations of adiponectin. The findings indicate the presence of an inverse relationship between serum concentrations of adiponectin and subclinical carotid atherosclerosis in patients undergoing CABG. In these patients, the absence of a significant correlation between severity of coronary atherosclerosis and adiponectin might suggest that adiponectin levels may predict the early stages rather than further progression of atherosclerosis.