Helicobacter pylori masks differences in homocysteine plasma levels between controls and type 2 diabetic patients.

BACKGROUND: Data in the literature have not clarified whether type 2 diabetes mellitus affects homocysteine plasma levels. Different variables able to influence homocysteine could be the cause of these controversial findings. An important but neglected confounding factor is Helicobacter pylori, which has been demonstrated to be a cause of elevated levels of homocysteine and which is prevalent in the Caucasian population, ranging from 30 to 40% incidence. Starting from these findings we wanted to verify whether differences in homocysteine levels exist between a type 2 diabetic population and a control group, taking into account the presence/absence of Helicobacter pylori. DESIGN: The study was carried out on a group of uncomplicated and normotensive type 2 diabetic patients (n = 30, 55.7 +/- 9.7 years) and on a control group (n = 43, 51.2 +/- 11.3 years). On these subjects we evaluated: main parameters of glyco- and lipo-metabolic balance, presence of Helicobacter pylori by 13C Urea Breath Test, plasma homocysteine, vitamin B12, folate and genetic polymorphism of methylenetetrahydrofolate reductase. RESULTS: Evaluating the two groups as a whole, significant differences in homocysteine were found when considering Helicobacter pylori presence/absence (14.0 +/- 6.5 vs. 10.6 +/- 4.7 micromol L-1, respectively, P < 0.01) without differences of vitamins and the genetic polymorphism of methylenetetrahydrofolate reductase. The positive interaction found among Helicobacter pylori, diabetes and homocysteine (P = 0.03) taking into account all the other evaluated confounding factors, demonstrates that a significant difference in homocysteine plasma levels exists between diabetics and controls (Helicobacter pylori-negative: diabetics 12.5 +/- 5.6 micromol L-1, controls 9.4 +/- 3.8 micromol L-1; Helicobacter pylori-positive: diabetics 13.6 +/- 5.8 micromol L-1, controls 14.3 +/- 7.0 micromol L-1). CONCLUSIONS: Type 2 diabetes seems to induce per se higher levels of homocysteine, which appears to be one of the factors responsible for the increased risk of vascular damage.

Fibronectin and lipoprotein(a) are inversely related to plasminogen activator inhibitor type-1 levels in Type 2 diabetic patients without complications.

Plasminogen activator inhibitor type-1 (PAI-1), the most important physiological fibrinolysis inhibitor, is considered an independent factor of cardiovascular risk in Type 2 diabetes mellitus (T2DM). In previous papers we demonstrated that a T2DM population without complications presents: 1) PAI-1 not increased with respect to a control group; and 2) a negative correlation between PAI-1 and lipoprotein(a) [Lp(a)], suggesting that in these subjects PAI-1 levels could be modulated by the "endothelial stress" induced by Lp(a) and diabetes. This work has been performed in order to better verify this intriguing hypothesis, and the endothelial stress has been evaluated through a marker of endothelial damage, fibronectin (FNC). For this purpose we chose a T2DM population without complications (n=73) and a control group (n=46). Plasma concentrations of FNC, Lp(a), PAI-1 antigen and activity, and the main parameters of lipo- and glycometabolic balance were determined. Fibronectin was significantly higher in diabetics with respect to controls (p<0.01). As expected, significant correlation between PAI-1 antigen, PAI-1 activity and Lp(a) (r=-0.54,p<0.01 and r=-0.39,p<0.01, respectively) was found only in diabetic patients. In the same group FNC showed a significant correlation with PAI-1 antigen and activity (r=-0.49,p<0.01 and r=-0.47; p<0.01, respectively), while no relationship was found between Lp(a) and FNC. Multiple regression analysis showed statistically significant correlation between PAI-1 antigen and PAI-1 activity with FNC and Lp(a) in diabetic patients without complications (p<0.05). These data suggest that in absence of complications, the endothelium is able to modulate PAI-1 levels, favouring in that way the fibrinolytic pathway and, subsequently, the recovery of the endothelial integrity. This modulation seems to be related to parameters such as Lp(a) and FNC, although the mechanisms of the endothelial stress of these two molecules seem to be different.

One- and two-compartment minimal models detect similar alterations of glucose metabolism indexes in hypertension.

A standard intravenous glucose tolerance test (IVGTT) was performed in 10 nondiabetic patients with essential hypertension (H group) and 9 normotensive control subjects (N group). A 2-compartment minimal model (2CMM) of glucose kinetics was applied to estimate indexes of glucose effectiveness, S2G and insulin sensitivity, S2I, by means of a maximum a posteriori (MAP) bayesian estimation technique. These estimates were contrasted to the S1G and S1I indexes provided by the classic minimal model (1CMM). In both the N group and the H group, the 2CMM underestimated the glucose effectiveness and overestimated the insulin sensitivity. In the H group, S2G was, on average, 63% of S1G (P > .05) and S2I was 137% of S1I (P > .05). In the N group S2G was 67% of S1G (P > .05) and S2I was 134% of S1I (P > .05). The 2CMM detected a reduction of approximately 40% (P > .05) and approximately 48% (P > .05) in S2G and S2I estimates, respectively, from the N group to the H group. Despite its reduced complexity, the 1CMM also detected a reduction of approximately 35% (P < .05) and approximately 49% (P < .05) in the S1G and in S1I indexes, respectively. Thus, the 1CMM and 2CMM showed a substantial equivalence in detecting a severe reduction in insulin sensitivity and impaired glucose effectiveness in hypertensive patients compared with normal.

Influence of body mass on glycemic control in a type 2 diabetic population: a 3-year follow-up.

Obesity is often associated with type 2 (non insulin-dependent) diabetes. A growing body of evidence support the hypothesis that these two diseases share a common pathogenesis. Nevertheless, experience derived from clinical observation on type 2 diabetic patients indicates that reduction of body weight is not always accompanied by an improvement in metabolic control and that a good metabolic control is often obtained without influencing body composition. Aim of the present study was to evaluate the relationship between body mass and glycemic control in a type 2 diabetic population by a 3 years observational study. A cohort of 562 subjects was studied. At entry more than 80% of patients were overweight or obese according to the body mass index (BMI) scale and this proportion was not significantly reduced at the end of the follow-up. At entry all patients had a glycosylated hemoglobin (HbA1c) value above 8.1% whereas at the end of follow-up more than 2/3 of patients were in good metabolic control. No relationship was observed between modification of body mass and metabolic control. These data confirm the high frequency of obesity among type 2 diabetic individuals but they suggest that impaired glucose metabolism and alteration of body weight have different pathogenesis.

Modifications induced by LDL from type 1 diabetic patients on endothelial cells obtained from human umbilical vein.

The aim of the present work was to analyze the effect of LDL obtained from type 1 diabetic patients in good metabolic control on human umbilical vein endothelial cells (HUVECs) after a short incubation period to detect possible atherogenic modifications of endothelial properties. Cultured HUVECs were incubated for 3 h with culture medium alone (control HUVEC), with native LDL from 12 healthy men (control LDL), or with native LDL from 12 type 1 diabetic men (type 1 LDL) (100 pg/ml). After the incubation, the following parameters were evaluated: nitric oxide synthase (NOS) activity, cytoplasmic Ca2+ levels, Na+-K+-ATPase activity, plasma membrane fluidity determined by means of 1,6-diphenyl-1,3,5-hexatriene (DPH) and 1-(4-trimethylaminophenyl)-6-phenyl-1,3,5-hexatriene (TMA-DPH), and plasma membrane conjugated diene (CD) content. The same experiments were repeated after bradykinin stimulation or in the presence of the antioxidant butylated hydroxytoluene (BHT), and nitric oxide (NO) production in intact HUVECs was also evaluated. HUVECs incubated with control LDL in comparison with control HUVECs showed a decreased fluidity of the membrane surface evaluated by TMA-DPH and a higher CD content. These alterations were prevented by the presence of BHT. HUVECs incubated with type 1 LDL in comparison with both control HUVECs and cells incubated with control LDL showed 1) increased NOS and Na+-K+-ATPase activity, cytoplasmic Ca2+ levels, and CD content, and 2) decreased fluidity of the membrane surface evaluated by TMA-DPH. These modifications were blunted--but not abolished--by the presence of BHT. After bradykinin stimulation either in the absence or in the presence of BHT, both cytoplasmic Ca2+ levels and NO production were increased in control HUVECs and in HUVECs incubated with control LDL, while a reduced response was observed in HUVECs incubated with type 1 LDL. The alterations observed in the endothelial function after the cell-LDL interaction might play a central role in the atherogenic process in diabetes.

Coronary heart disease, type 2 diabetes mellitus and cardiovascular disease risk factors: a study on a middle-aged and elderly population.

The risk for all the manifestations of atherosclerotic disease is increased in patients affected by type 2 diabetes mellitus. The aim of the present work was to evaluate the prevalence of coronary heart disease (CHD) in a well-characterized middle-aged and elderly Italian diabetic population. The population studied included 3862 subjects, i.e. all the patients affected by type 2 diabetes of age >or=50 years attending the outpatient diabetes care unit of INRCA in Ancona (Italy) from 1 August 1997 to 31 July 1998. We collected and analysed both clinical and laboratory data by means of a computerized data base for the outpatient clinic management. The prevalence rate of CHD was 20.25% in this population. The groups with CHD and without CHD did not differ significantly with respect to age at onset of diabetes, body mass index and HbA1c levels, while patients with CHD were significantly older than patients without CHD and had a longer duration of diabetes. The prevalence of patients with hypertension (52.9 vs 63.0%, P<0.001), hypercholesterolemia (11.6 vs 14.1%, P<0.05) and hyperlipidemia (17.8 vs 23.3%, P<0.001) was significantly higher in the group of diabetic subjects affected by CHD than in patients not affected by heart ischemic disease. It might be hypothesized that the improvement of metabolic profile and the currently feasible control of non-diabetic risk factors could reduce cardiovascular disease rates in type 2 diabetic patients.