vitamin-b-12 and Hyperinsulinism

The purpose of this study was (a) to study whether a folate and vitamin B12 treatment, aimed at decreasing homocysteine levels, might ameliorate insulin resistance and endothelial dysfunction in patients with metabolic syndrome according to the National Cholesterol Education Program-Adult Treatment Panel-III criteria and (b) to evaluate whether, under these metabolic conditions, there is a relationship between hyperhomocysteinemia and insulin resistance.. A double-blind, parallel, identical placebo-drug, randomized study was performed for 2 months in 50 patients. Patients were randomly allocated to two groups. In group 1, patients were treated with diet plus placebo for 2 months. In group 2, patients were treated with diet plus placebo for 1 month, followed by diet plus folic acid (5 mg/day) plus vitamin B12 (500 microg/day) for another month.. In group 2, folate treatment significantly decreased homocysteine levels by 27.8% (12.2+/-1.2 vs 8.8+/-0.7 micromol/l; P<0.01). A significant decrement was observed for insulin levels (19.9+/-1.7 vs 14.8+/-1.6 microU/ml; P<0.01) accompanied by a 27% reduction in the homeostasis model assessment levels. A positive relationship was found between the decrement of homocysteine and insulin levels (r=0.60; P<0.002). In parallel, endothelial dysfunction significantly improved in the treated group, since post-ischemic maximal hyperemic vasodilation increased by 29.8% and cGMP by 13.6% while asymmetrical dimethylarginine levels decreased by 21.7%. On the contrary, in group 1 patients, treated with placebo, no changes were shown in any of the variables.. Folate and vitamin B12 treatment improved insulin resistance and endothelial dysfunction, along with decreasing homocysteine levels, in patients with metabolic syndrome, suggesting that folic acid has several beneficial effects on cardiovascular disease risk factors.

Topics: Aged; Drug Therapy, Combination; Endothelium, Vascular; Female; Folic Acid; Hematinics; Homocysteine; Humans; Hyperinsulinism; Male; Metabolic Syndrome; Risk Factors; Vitamin B 12

In order to evaluate the clinical characteristics of metabolic syndrome, a screening procedure was performed and in a cohort of middle-aged (40-60 years) hyperinsulinaemic (fasting plasma insulin > 15 microU/ml) and/or postprandial [120 min after 75 g glucose load] insulin > 45 microU/ml) subjects (n = 91; men/women: 38/53; age mean +/- SD 47.6 +/- 4.3 years; body mass index: 34.6 +/- 4.9 kg/m2; waist-hip ratio: 0.92 +/- 0.07; actual blood pressure 146 +/- 16/87 +/- 9 mmHg; fasting insulin: 24.2 +/- 11.3 microU/ml; postprandial insulin 125.5 +/- 103.8 microU/ml; serum LDL-cholesterol: 3.73 +/- 1.09 mmol/l; HDL-cholesterol: 1.12 +/- 0.30 mmol/l; triglycerides: 2.97 +/- 2.38 mmol/l; uric acid 279 +/- 79 mumol/l) plasma fasting homocysteine, vitamin B12 and folic acid levels were simultaneously determined. The values were separately evaluated according to the stages of glucose tolerance (normal glucose tolerance [n = 47]; impaired glucose tolerance [n = 24] and diabetes mellitus [n = 20]). Laboratory normal values were determined in 47 healthy subjects (control group, age: 45.0 +/- 7.8 years, men/women: 19/28). There was no significant difference between hyperinsulinaemic and control subjects regarding plasma homocysteine (9.28 +/- 3.81 mumol/l vs. 9.63 +/- 2.70 mumol/l), folic acid (8.5 +/- 5.9 ng/ml vs. 7.5 +/- 2.1 ng/ml) and vitamin B12 levels (423 +/- 141 pg/ml vs. 356 +/- 121 pg/ml). Plasma homocysteine levels were significantly (p < 0.001) higher in hyperinsulinaemic men than women (11.34 +/- 4.72 mumol/l [n = 38] vs. 7.86 +/- 2.13 mumol/l [n = 53]). There was no significant difference between subgroups classified according to the stages of glucose tolerance in hyperinsulinaemic groups. Plasma homocysteine values exceeding the upper limit of normal range (> 12.45 mumol/l) were detected at a similar prevalence rate in control (4/47 = 8.5%) and in hyperinsulinaemic subjects (10/91 = 10.9%). A weak but statistically significant correlation was found between plasma homocysteine values and age of subjects (r = 0.222; p < 0.05) whereas a stronger correlation was documented between plasma homocysteine and serum creatinine values (r = 0.658; p < 0.001) in hyperinsulinaemic groups (n = 91). Plasma homocysteine values independently from the stages of glucose tolerance are not elevated in hyperinsulinaemic subjects. Hyperhomocysteinaemia is not a characteristic feature of hyperinsulinism suggesting that plasma homocysteine levels are of no considerable importance

Topics: Adult; Blood Glucose; Cohort Studies; Female; Folic Acid; Glucose Tolerance Test; Homocysteine; Humans; Hyperinsulinism; Male; Middle Aged; Severity of Illness Index; Sex Factors; Vitamin B 12