Effects of the naturally-occurring disaccharides, palatinose and sucrose, on incretin secretion in healthy non-obese subjects.

AIMS/INTRODUCTION: Incretins might play some pathophysiological role in glucose metabolism in diabetes and obesity; it is not clear whether or not the amount and the pattern of incretin secretion vary with different types of sugars. To evaluate the effect of two types of disaccharides on glucose metabolism and the kinetics of incretin secretion, plasma levels were measured after palatinose or sucrose ingestion in non-obese healthy participants. MATERIALS AND METHODS: The study was carried out on healthy participants who were given a solution containing 50 g of palatinose or sucrose for ingestion. Blood samples were obtained before loading and after ingestion. Insulin, glucagon and incretins hormones were measured by the enzyme-linked immunosorbent assay method. RESULTS: When the data were compared between palatinose and sucrose ingestion, both plasma glucose values at 15, 30 and 60 min, and plasma insulin values at 15 and 30 min after palatinose loading were significantly lower than those after sucrose loading. Plasma levels of total glucose-dependent insulinotropic polypeptide at 15-90 min after palatinose loading were significantly lower than those after sucrose loading. Plasma levels of total and active glucagon-like peptide-1 at 90 min and the area under the curve (60-120 min) of the total glucagon-like peptide-1 were significantly higher with palatinose-loading than with sucrose loading. CONCLUSION: Compared with sucrose, palatinose appears to have a more favorable effect on glucose metabolism and protection of pancreatic islets as a result of less hyperglycemic and hyperinsulinemic potency.

Association between insulin resistance and endothelial dysfunction in type 2 diabetes and the effects of pioglitazone.

Endothelial dysfunction is regarded as an early stage of atherosclerosis, and plays a role in the development of atherosclerotic diseases. Insulin resistance is related to the atherosclerotic process. In this study, we examined the association between endothelial function and insulin resistance in 48 subjects with type 2 diabetes. In addition, the effects of pioglitazone treatment on endothelial function and insulin resistance were investigated in a subgroup of subjects. Endothelial function of the brachial artery was non-invasively assessed using ultrasound technique. We measured flow-mediated endothelium-dependent vasodilation (FMD) and glyceryl trinitrate-induced endothelium-independent vasodilation (GTN). Insulin sensitivity was measured by the steady-state plasma glucose (SSPG) method. High SSPG levels indicate insulin resistance. There was a significant inverse correlation (r=-0.462, p<0.001) between SSPG and FMD. Systolic blood pressure was inversely correlated with FMD (r=-0.360, p<0.013). By multiple regression analysis, insulin resistance was the sole predictor of FMD. The effects of chronic treatment with pioglitazone were assessed in 10 subjects with type 2 diabetes. The increase in FMD significantly correlated with the decrease in SSPG. There is a significant association between vascular endothelial dysfunction and insulin resistance in type 2 diabetes. This result was supported by the effects of the insulin sensitizer, pioglitazone.

Development of cookie test for the simultaneous determination of glucose intolerance, hyperinsulinemia, insulin resistance and postprandial dyslipidemia.

A new cookie test was developed for the simultaneous evaluation of multiple risk factors such as glucose intolerance, hyperinsulinemia, insulin resistance and postprandial dyslipidemia. The cookie consisting of 75 g carbohydrate and 25 g fat is ingested and the blood samples are obtained at 0, 1 and 2 hours later. When the two carbohydrate sources, liquid glucose and test cookie, were compared as a glucose load within 3 months, the 2 hr plasma glucose levels were not statistically different, proposing the use of the same criteria at 2 hour glucose level for the diagnosis of diabetes and impaired glucose tolerance (IGT) in subjects without exocrine pancreatic dysfunction. In addition, hyperinsulinemia, insulin resistance (AUC insulin, and/or AUC insulin X AUC glucose), and postprandial hyperlipidemia (DeltaTG, Triglyceride; DeltaRLP, remnant like particles) have been simultaneously uncovered. Reactive hypoglycemia with adverse epigastric discomfort was observed in 26.3% of the control subjects with liquid glucose, while it was observed in only 1 case (5.3%) without any symptom with cookie tests. In fact, one reactive hypoglycemia out of 5 with liquid glucose turned out to be IGT with cookie test. In 64 subjects with lifestyle-related diseases, cookie test revealed hyperinsulinemia and insulin resistance in 56% respectively, postprandial hyperlipidemia in 39%, diabetes and IGT in 22-23% of each of the subjects and all showed at least one abnormal value. In contrast, in university students with exercise habit, all showed normal results with cookie test. In addition, improved insulin sensitivity over non-exercise group was obverved. In summary, the cookie test provided more informations compared with OGTT using liquid glucose and with fewer side effects. Simultaneous evaluation of glucose intolerance, hyperinsulinemia, insulin resistance, and postprandial hyperlipidemia was also possible.

Intensive treatment of risk factors in patients with type-2 diabetes mellitus is associated with improvement of endothelial function coupled with a reduction in the levels of plasma asymmetric dimethylarginine and endogenous inhibitor of nitric oxide synthase.

AIMS: Vascular endothelium is a major organ involved in hyperglycaemia and is affected by plasma asymmetric dimethylarginine (ADMA). ADMA is an endogenous, competitive inhibitor of nitric oxide synthase and is induced by inflammatory cytokines of tumour necrosis factor (TNF)-alpha in vitro. We hypothesized that a tight glycaemic control may restore endothelial function in patients with type-2 diabetes mellitus (DM), in association with modulation of TNF-alpha and/or reduction of ADMA level. METHODS AND RESULTS: In 24 patients with type-2 DM, the flow-mediated, endothelium-dependent dilation (FMD: %) of brachial arteries during reactive hyperaemia was determined by a high-resolution ultrasound method. Blood samples for glucose, cholesterol, TNF-alpha, and ADMA analyses were also collected from these patients after fasting. No significant glycaemic or FMD changes were observed in 10 patients receiving the conventional therapy. In 14 patients who were hospitalized and intensively treated, there was a significant decrease in glucose level after the treatment [from 190+/-55 to 117+/-21 (mean+/-SD) mg/dL, P<0.01]. After the intensive control of glucose level, FMD increased significantly (from 2.5+/-0.9 to 7.2+/-3.0%), accompanied by a significant (P<0.01) decrease in TNF-alpha (from 29+/-16 to 11+/-9 pg/dL) and ADMA (from 4.8+/-1.5 to 3.5+/-1.1 microM/L) levels. The changes in FMD after treatment correlated inversely with those in TNF-alpha (R=-0.711, P<0.01) and ADMA (R=-0.717, P<0.01) levels. CONCLUSION: The intensive correction of hyperglycaemia is associated with the improvement of endothelial function, which is coupled with the decrease in the levels of reduction of plasma TNF-alpha and ADMA in patients with type-2 DM. A strict glycaemic control may exert anti-cytokine and anti-atherogenic effects and may therefore be pathophysiologically important.

Close association of endothelial dysfunction with insulin resistance and carotid wall thickening in hypertension.

BACKGROUND: Endothelial dysfunction has been regarded as an early stage in the atherosclerotic process. Endothelial dysfunction and insulin resistance were observed in hypertensive subjects and were associated with carotid wall thickening. METHODS: We examined the determinants of endothelial dysfunction including insulin sensitivity and carotid wall thickening. A total of 41 subjects with nondiabetic essential hypertension were studied. Endothelial function of brachial artery and carotid wall thickening were assessed noninvasively using ultrasound technique. In brachial artery, we measured flow-mediated endothelium-dependent vasodilation (FMD) and glyceryl trinitrate-induced endothelium-independent vasodilation (GTN). We estimated intima-media thickness of the common carotid artery (IMT). Insulin sensitivity was measured according to the steady-state plasma glucose (SSPG) method. High SSPG levels indicated insulin resistance. RESULTS: On univariate analysis, there were significant negative correlations between FMD and SSPG (r = -0.695, P <.0001) or IMT (r = -0.449, P <.004). The FMD was negatively correlated significantly with age and with systolic and diastolic blood pressures (BP). A significant negative correlation was observed between GTN and SSPG. There was a significant positive relation between SSPG and IMT. On multiple regression analysis including systolic BP, SSPG, and age as independent variables and FMD as a dependent variable, FMD was independently related to SSPG (P <.03) and systolic BP (P <.02). If the presence of SSPG, diastolic BP, and age were entered as independent variables against FMD, FMD was independently related to SSPG (P <.002). CONCLUSIONS: One of the major determinants of endothelial function was insulin resistance. Our findings suggest that endothelial dysfunction and early structural vascular changes were related to insulin resistance.

[Development of the cookie test for the early detection and analyses of metabolic risk factors of the life style related diseases and its significance].

While with toleranG 30% of the healthy subjects showed reactive hypoglycemia(2 h BS below 80 mg/dl) with symptoms, with cookie tests none showed hypoglycemia nor adverse effect. In National Cardiovascular Center, the rate of reactive hypoglycemia was 4.1% and in those with 2 h BS below 50 mg was 0.5%. The incidence seemed to be various according to the insulin reserve of pancreatic beta-cells. In subjects with life style related disorder, additional abnormalities other than basal were revealed together with insulin resistance(AUCInsulin, AUCInsulin x AUCGlucose). In subjects with exercise habit, who exhibited lower energy expenditure at rest but higher VO2max, shwoed smaller increase of blood glucose and insulin above basal on cookie test, indicating increased insulin sensitivity. A new snack test in subjects without exocrine pancreatic disorder serves natural carbohydrate(75 g) and fat source(24 g). The test has less adverse effects, like reactive hypoglycemia. The test revealed glucose intolerance, diabetes, hyperinsulinemia, postprandial dyslipidemia and insulin resistance more efficiently than in the routinely performed OGTT (liquid glucose) or fat loading test.

[Evaluation of SMBG values using various instruments and clinical significance of forearm SMBG measurement].

Whole blood or plasma glucose values were compared between those measured using various instruments for SMBG and automated analyses in samples (antecubital vein) from 20 approximately 70 years old obtained at cookie tests. A good correlation between values in whole blood SMBG and plasma automated analyses values greater than r = 0.94 was observed for instruments A, C, F, and H, and the per cent difference from the automated values was less than 5% for A, B, E and H. Per cent difference of SMBG values by I was -16% in whole blood and -9% in plasma, suggesting the possibility of measuring real values in whole blood. With plasma, a good correlation greater than r = 0.95 was noted for A, C, F and K, and the per cent difference less than 10% was noted for C, E, F and I. A relatively good correlation (r: 0.63 approximately 0.90) between forearm SMBG value and plasma automated values was noted with the % difference of the mean less than 11%. During cookie test, there is no significant difference between forearm SMBG values and antecubital plasma automated values. Values at finger tips are significantly greater by 5 approximately 20% over automated plasma values. In conclusion, whole blood values by most of the SMBG instruments are well correlated with plasma automated values, although some disagreement was noted. Values at forearm are not different from plasma val ues of antecubital vein, while at finger tip SMBG values showed higher levels. The measurement at forearm is therefore recommended, and in addition the pain is less.

Improvement of insulin sensitivity by a long-acting nifedipine preparation (nifedipine-CR) in patients with essential hypertension.

BACKGROUND: Nifedipine has been reported to cause impairment of insulin sensitivity. But recently a controlled-released formulation of nifedipine (nifedipine-GITS) has been reported that it could improve insulin sensitivity. METHODS: We evaluated insulin sensitivity in two groups of essential hypertensive subjects before and after treatment with either long-acting nifedipine (nifedipine-CR, Adalat CR tablets; Bayer Yakuhin, Osaka, Japan) (n = 10) or metoprolol (n = 9). Insulin sensitivity was evaluated from the steady-state plasma glucose (SSPG) level measured at the steady-state insulin level (20 to 30 microU/mL) using a modification of the SSPG method previously reported. RESULTS: The SSPG was initially high, but was significantly reduced by nifedipine-CR treatment (from 133 +/- 14 mg/dL to 95 +/- 8 mg/dL). However, SSPG was not significantly altered by treatment in the metoprolol group (from 103 +/- 15 mg/dL to 119 +/- 12 mg/dL). CONCLUSIONS: Our results indicate that the long-acting nifedipine (nifedipine-CR) is associated with improved insulin sensitivity.

Multifactorial insulin resistance and clinical impact in hypertension and cardiovascular diseases.

Insulin resistance and hyperinsulinemia have been observed in over 70% of the nonobese, nondiabetic subjects with essential hypertension (HT). Alpha-1 blockers, ACE-antagonists, long-acting Ca blockers including nifedipine CR, some form of beta-blockers, tilisolor, which is reported to increase blood flow, improve insulin sensitivity when blood pressure is better controlled. Decrease of serum potassium during insulin sensitivity test and intraplatelet free Ca2+ concentration is positively and negatively correlated with insulin sensitivity, respectively. Blood pressure is correlated with insulin resistance, which is also observed in secondary HT. The resistance is correlated with salt sensitivity as well as impaired nocturnal fall of blood pressure. These suggest the possible association of insulin resistance with altered intracellular cation metabolism. Insulin resistance and associated hyperinsulinemia have been observed in effort as well as vasospastic angina pectoris (VSAP), atherothrombotic cerebral infarction, and in ASO without obesity, HT, or diabetes, suggesting the resistance resulting from endothelial dysfunction. Insulin resistance has been observed in heart failure and is correlated with angiotensin II. Resistance is also observed in hypertrophic cardiomyopathy and is partially correlated with TNF-alpha. These results indicate that insulin resistance seem to be multifactorial. An effort to normalize insulin sensitivity is crucial to eliminate multiple risk factors as well as to prevent the progression of atherosclerotic vascular lesions.