Acute-phase glucose fluctuation is negatively correlated with myocardial salvage after acute myocardial infarction.

BACKGROUND: It remains unclear whether glycemic fluctuation immediately after acute myocardial infarction (AMI) can affect myocardial damage. This study investigated the impact of glucose fluctuation on myocardial salvage following successful recanalization of primary AMI. METHODS AND RESULTS: A total of 36 consecutive patients with AMI were studied. Glycemic variability, as indicated by the mean amplitude of glycemic excursion (MAGE), was measured on a continuous glucose monitoring system. Three subsets (CD14(+)CD16(-), CD14(++)CD16(+) and CD14(+-)CD16(+)) were measured on flow cytometry 1, 2, 3, 4 and 5 days after AMI onset. A 2-h oral glucose test was performed in 23 patients who had no previous diagnosis of diabetes and/or glycated hemoglobin <6.5%, after the onset of AMI at 2 weeks. Plasma active glucagon-like peptide (GLP)-1 level was measured in each sample. The extent of myocardial salvage 7 days after AMI was evaluated on cardiovascular magnetic resonance imaging. MAGE and the peak CD14(+)CD16(-) monocyte level were significantly negatively correlated with myocardial salvage index (MSI). MAGE was significantly correlated with peak CD14(+)CD16(-) monocyte level. Of interest, plasma GLP-1 level was significantly positively correlated with MSI and significantly negatively correlated with MAGE. CONCLUSIONS: Glucose fluctuations during the acute phase of AMI affect MSI, indicating that manipulation of glucose variability from peak to nadir might be a potential therapeutic target for salvaging ischemic damage.

Combined examination of glyceryl trinitrate-mediated vascular dilation with flow-mediated vascular dilation is essential for assessment of vascular function in type 2 diabetes.

AIMS/INTRODUCTION: In order to characterize the impaired vascular function in type 2 diabetes (DM) patients, we evaluated the flow-mediated vascular dilation (FMD) with glyceryl trinitrate-mediated vascular dilation (NMD) using ultrasonography. MATERIALS AND METHODS: A total of 111 DM patients and 42 healthy control participants were studied. The maximal dilatation of FMD and NMD (%FMD and %NMD, respectively), the beginning time (T) of dilatation after stimulation and the velocity (V) of the vascular dilatation were also measured. RESULTS: Among DM patients, 49% had impaired %NMD, which affects the results of %FMD. In DM patients with normal %NMD, the %FMD was also significantly lower than that in control participants, although the T and the V were not impaired. In contrast, both the T and the V were disturbed in the DM patients with low %NMD. Multiple linear regression analysis showed that %NMD was independently correlated with albuminuria. Our results indicate that the impaired FMD in DM is be affected by low NMD, and impaired endothelial function already exists even in DM patients whose vascular smooth muscle function is still retained, and also albuminuria is the clinical feature of DM with low %NMD. CONCLUSIONS: Examination of NMD, not only FMD, should be carried out as it offers the possibility of clarifying vascular function in DM patients.

Protective role of human insulin against the cytotoxicity associated with human mutant S20G islet amyloid polypeptide.

AIMS/INTRODUCTION: Islet amyloid polypeptide (IAPP) is a main component of islet amyloid in type 2 diabetes and cosecreted from ß-cell with insulin. Clinical evidence from the patients with S20G mutation of the IAPP gene, as well as experimental evidence that insulin could inhibit amyloid formation of IAPP, suggests that a gradual reduction of insulin could be related to the cytotoxicity associated with S20G-IAPP through long-term deterioration of ß-cells in type 2 diabetes. Our objective was to show an effect of human insulin on S20G-IAPP associated cytotoxicity. MATERIALS AND METHODS: We analyzed the cytotoxicity associated with S20G-IAPP by controlling human insulin expression using adenovirus vectors with micro ribonucleic acid specifically against human insulin in endocrine AtT-20ins cells, which express human insulin permanently. Additionally, we carried out a follow-up study of circulating IAPP and insulin in type 2 diabetic patients. RESULTS: S20G-IAPP expression was associated with a decrease in viability and an increase in terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick end labeling-positive cells in AtT-20ins cells. Furthermore, downregulation of human insulin enhanced the cytotoxicity associated with S20G-IAPP, and induced the cytotoxicity associated with wild-type (WT)-IAPP. Reduction of ubiquitin carboxy-terminal hydrolase L1 activity enhanced cytotoxicity under the downregulation of human insulin expression in both S20G- and WT-IAPP transduced cells. A 5-year follow up of type 2 diabetic patients showed a disproportionate increase of serum fasting IAPP-to-insulin ratio from baseline. CONCLUSIONS: Human insulin plays a protective role against the cytotoxicity associated with S20G-IAPP, as well as WT-IAPP. The findings could suggest long-term deterioration of insulin secretion associates with IAPP linked cytotoxicity in type 2 diabetes.

[Evaluation of seasonal changes in hemoglobin A1c in diabetic patients].

In order to evaluate seasonal changes in hemoglobin A1c (HbA1c) values, we examined HbA1c values among 34,590 patients in 2010, and calculated the monthly average of HbA1c values through the year. HbA1c values were the highest in March and the lowest in October with a difference of 0.30%. The similar annual pattern was observed in HbA1c values from 2006 to 2009. Then we selected 453 diabetic patients whose treatment did not change through the year, and calculated average HbA1c values in four seasons each. There were also significant seasonal changes in diabetic patients, which were the highest in the spring and the lowest in the autumn, especially found in patients with insulin therapy. These effects may be caused by cold climate, decreased physical activity, over food intake and body weight gain in the winter. These seasonal changes in HbA1c should be concerned in the case of health service research, clinical trials and evaluation of the effects of medical treatment.

[Clinical evaluation of insulin measuring kit not cross-react with insulin analogue preparations].

Clinical evaluation of insulin assay system reacting with only human insulin molecule (kit B) was performed by comparing it with conventional insulin assay system (kit A) cross-reacting with insulin analogue as well as human insulin preparation. In vitro, the kit B was confirmed to cross-react with only human insulin, not with insulin analogue preparations such as insulin aspart, lyspro and glargine. In non-insulin treated diabetic patients, postprandial and post-insulin injected serum immunoreactive insulin (IRI) concentrations measured by kit B were almost the same as those measured by the kit A. On the other hand, in diabetic patients treated with insulin analogue preparations, postprandial and post-insulin injected serum IRI levels measured by kit B were obviously low compared with those by kit A. After intravenous injection of insulin analogue preparations (0.1 unit/kg), insulin lyspro or insulin aspart, serum IRI levels measured by the kit B were not increased but gradually decreased in contrast to the obviously increased serum IRI level measured by the kit A. From these results, the kit B was confirmed not to measure the insulin analogue preparations in vitro and in vivo.

Progressive deterioration of insulin secretion in Japanese type 2 diabetic patients in comparison with those who carry the S20G mutation of the islet amyloid polypeptide gene: A long-term follow-up study.

UNLABELLED: Aims/Introduction: In order to clarify the enhanced ß-cell dysfunction in type 2 diabetic patients carrying the S20G mutation of the islet amyloid polypeptide gene (S20G-patients), we first estimated the decline of insulin secretion in Japanese type 2 diabetic patients without the S20G mutation (non-S20G-T2D-patients) by long-term observation, and then compared it with that of the S20G-patients. MATERIALS AND METHODS: We followed 70 non-S20G-T2D-patients (body mass index <30 kg/m(2)) for more than 10 years and six S20G-patients for more than 5 years. We measured fasting C-peptide (F-CP) every 1-2 years and carried out a glucagon test at least once during the follow-up period. F-CP and a 5-min value of C-peptide after glucagon injection (5'-CP) were used as the indices of insulin secretion. We excluded patients who had renal dysfunction and/or anti-insulin antibodies in the insulin-treated patients. The individual annual declines were calculated from the slopes of the regression lines between C-peptide levels and duration (years after diagnosis). RESULTS: The mean individual annual declines of both F-CP and 5'-CP were significantly greater in the S20G-patients than the non-S20G-T2D-patients (F-CP; 0.047 ± 0.026 vs 0.011 ± 0.037 nmol/L/year, P = 0.025, 5'-CP; 0.139 ± 0.055 vs 0.022 ± 0.012 nmol/L/year, P = 0.008). CONCLUSIONS: We established the annual decline of insulin secretion in the Japanese type 2 diabetic patients by the long-term observation. The results show that the decline of insulin secretion is more rapid in the S20G-patients than the non-S20G-T2D-patients. (J Diabetes Invest, doi: 10.1111/j.2040-1124.2011.00102.x, 2011).

[Clinical usefulness of measurement of urine type IV collagen for detection of early phase of nephropathy in type 2 diabetic patients].

Urine type IV collagen concentrations in type 2 diabetic patients were measured by enzyme immunoassay which has crossreactivity with only intact type IV collagen, and the clinical usefulness for estimating the early phase of diabetic nephropathy was evaluated. Precision of the measurement system was satisfactory for clinical use and the value did not influenced by the presence of sediments in urine. In whole type 2 diabetic patients (N=132), urine type IV collagen concentration (microg/g of creatinine) increased with development of nephropathy and showed significantly increase even in normoalbuminuria when compared with that in normal control subjects (N=117). In type 2 diabetic patients (N=100) with mild microalbuminuria (less than 100 mg/g of creatinine), multiple regression analysis revealed that HbA1C was extracted as a significant valuable for urine type IV collagen, while body mass index was extracted as a significant valuable for urine albumin. In these subjects, urine type IV collagen was significantly lower in the patients with good metabolic control (HbA1C<8.0%) than those with poor control (HbA1> or =8.0%), while the urine albumin was not significantly different between those two groups. These results suggest that measurement of urine type IV collagen in type 2 diabetic patients is useful for detection of early phase of diabetic nephropathy.

[Clinical usefulness for measurement of plasma brain natriuretic peptide in diabetic patients].

Plasma brain natriutetic peptide (BNP) concentrations in type 2 diabetic patients were measured by newly developed enzyme immunoassay, and their clinical application was evaluated. Precision of the measurement system was satisfactory for clinical use, and the value obtained by this system had good correlation to that by radioimmunoassay. Tubes containing NaF in addition to EDTA, usually used for measurement of plasma glucose and HbA1c in diabetic patients, could be used for the collection of plasma sample. In 133 type 2 diabetic patients who had no symptom for heart failure, plasma BNP was elevated in those with ischemic heart disease and it was also significantly elevated even in the patients who had no ischemic change on double Master two-step exercise testing than that in control subjects. In 52 patients receiving the examination by cardiosonography, plasma BNP levels significantly correlated to the left ventricular mass index, and also had a significant correlation to peak flow velocity in early diastole/peak flow velocity in late diastole (E/A) ratio, one of a simple index for an asymptomatic diastolic heart failure. Multiple logistic regression analysis revealed that age and coronary heart disease were extracted as a significant valuable for plasma BNP level in type 2 diabetic patients. These results suggest that measurement of plasma BNP in type 2 diabetic patients was useful as a screening method for evaluating the latent deterioration of heart function such as asymptomatic ischemic heart disease.

Retinopathy and hypertension affect serum high-sensitivity C-reactive protein levels in Type 2 diabetic patients.

Several studies suggest that inflammation plays an important role in the pathogenesis of diabetes mellitus, as well as atherosclerosis, and acute-phase reactants have been proposed as monitors for the ongoing process of these diseases. We studied the clinical significance of serum high-sensitivity C-reactive protein (hs-CRP) in relation to chronic diabetic complications using 114 Japanese patients with Type 2 diabetes mellitus. The hs-CRP values were normalized by logarithmic transformation for statistical analysis. Retinopathy and hypertension were extracted as significant modulators for the hs-CRP value in the diabetic patients, in addition to previously known factors, age, and body mass index (BMI), by multivariate analysis. The hs-CRP level in normotensive diabetic patients without retinopathy was not significantly different from that of normal control participants after adjustment for age and BMI. The hs-CRP value was significantly high in the patients with hypertension, despite the existence or absence of diabetes. On the other hand, the hs-CRP level of the diabetic patients complicated with retinopathy was low especially in those with hypertension. The frequency of patients having an hs-CRP value above 1.0 mg/l who are thought to be at risk for cardiovascular diseases was also high in the patients complicated with hypertension and low in the diabetic patients with retinopathy. These results indicate that the presence or absence of hypertension and retinopathy should be taken into consideration for the interpretation of the serum hs-CRP in diabetic patients.