Improved Insulin Sensitivity and Metabolic Control in Type 2 Diabetes Does Not Influence Plasma Homocysteine

Abstract

Results from a population-based survey O ur objective was to evaluate the diagnostic proficiency of the World Health Organization (WHO) and the National Cholesterol Education Program (NCEP)-III definitions (1,2) for the metabolic syndrome in a Mexican nationwide, population-based survey. Details of the sampling procedures have been previously described (3). The population was composed of 2,158 men and women aged 20 -69 years sampled after a 9-to 12-h fasting period. For the WHO criteria, insulin resistance was diagnosed if a nondiabetic case had fasting insulin concentrations Ն126 pmol/l (21 U/ml) (Ͼ75th percentile in Mexican adults). The ageadjusted prevalence was 13.61% for the WHO criteria (n ϭ 268) and 26.6% for the NCEP-III definition (n ϭ 574). After excluding patients with diabetes, the prevalence was 9.2 and 21.4%, respectively. The agreement between the definitions was assessed in 1,969 subjects; 189 cases were eliminated due to the lack of a urine sample.The number of abnormal cases was lower using the WHO criteria. Only 237 of the 545 subjects (43.4%) who fulfilled the NCEP criteria were diagnosed as affected using the WHO definition. Just 16 of 253 cases (6.3%) detected by the WHO definition did not fulfill the NCEP definition. The agreement between the criteria was moderate ( ϭ 0.507). On the other hand, the subjects diagnosed using the WHO recommendations had a worse profile than the cases detected by the NCEP-III definition only-they had a higher BMI and higher non-HDL cholesterol, triglyceride, and glucose concentrations. The demonstration of insulin resistance among the nondiabetic population caused the lack of agreement in 202 of the 242 cases that fulfilled the NCEP definition but failed the WHO criteria. Other reasons for disparity were the higher thresholds used by the WHO criteria; these differences explained the lack of agreement in 66 of the 152 cases with diabetes.In conclusion, the prevalence of the metabolic syndrome is influenced by the selection of the diagnostic criteria. The WHO criteria identified a lower number of cases than the NCEP-III definition. These differences were explained mainly by the inclusion of abnormally high insulin concentrations as a diagnostic criterion. However, the presence of insulin resistance may help to identify patients more severely affected (4). We had previously assessed the effect of complete blockade of the renin-angiotensin system (RAS) in patients with advanced diabetic nephropathy (type 2 diabetes) and severe proteinuria (2). To do so, we studied 10 patients on prior treatment with ACE inhibitors at recommended doses, to which 50 mg/day of Losartan was added. CARLOS A. AGUILAR-SALINASAfter 3 months of the combined therapy, urinary protein excretion decreased from a mean of 6.9 (95% CI 4.3-9.6) to 5.8 g/24 h (3-8.6) (P ϭ 0.025) and, with the exception of two patients, was reduced in all cases. The proteinuria/ urinary creatinine ratio also decreased from 7.6 (4.2-11.05) to 6.0 g/g (3.2-8.7) (P ϭ 0.02). In one patient in which proteinuria did not ...

Insulin in methionine and homocysteine kinetics in healthy humans: plasma vs. intracellular models

“…Euglycemic hyperinsulinemia reduced plasma homocysteine concentrations in normal but not in type 2 diabetic subjects without, however, any dose-response effect (6). Conversely, the improvement of insulin sensitivity and metabolic control did not influence plasma homocysteine concentrations in type 2 diabetes (18). As a matter of fact, the issue of the regulation by insulin and/or insulin resistance conditions on homocysteine concentrations is still unresolved.…”

Relationship between Metabolic Syndrome Categorized by Newly Recommended by International Diabetes Federation Criteria with Plasma Homocysteine Concentration

“…Godsland et al [36] examined the association of homocysteine concentrations with insulin sensitivity, as measured by a glucose tolerance test, and with the components of metabolic syndrome in healthy males, and showed that homocysteine metabolism was not affected by insulin action. In addition, Abbasi et al and Pouwels et al [37,38] have reported that tHcy was unrelated with insulin resistance in healthy volunteers and diabetic subjects, even after the improvement of insulin sensitivity. In contrast, in a recent work by Bjorck et al analysed in a populationbased sample of Swedish subjects, positive association between serum insulin and serum Hcy independent of age and sex were observed [39], suggesting the possible link between the metabolic syndrome and Hcy.…”

Insulin resistance and endothelial function are improved after folate and vitamin B12 therapy in patients with metabolic syndrome: relationship between homocysteine levels and hyperinsulinemia

“…In addition, several case -control studies (15 -20) have shown that insulin levels are significantly related to homocysteine levels in various groups of patients, such as hypertensive patients with type 2 diabetes, obese patients, women with polycystic ovary syndrome and pregnant women with pre-eclampsia. In contrast, Abbasi et al (21) were unable to confirm such an association in a group of healthy subjects, and two other reports have indicated that an improvement in insulin sensitivity was not accompanied by an amelioration of homocysteine levels (22,23). Whereas a few studies in animals have suggested that insulin affects the activity of the key enzymes of homocysteine metabolism (24), little is known about the relationship between homocysteine and insulin sensitivity in humans.…”