Update on oral contraception

Analysis of the effect of multiple genetic variants of cardiovascular disease risk on insulin concentration variability in healthy adults of the STANISLAS cohort

INTRODUCTION

Given the hypothesis of a common soil for atherosclerosis, type 2 diabetes and metabolic syndrome, we tested the contribution of gene polymorphisms involved in cardiovascular diseases on fasting insulin concentration (FIC).

METHODS

The polymorphisms were investigated by a multiplex assay in 308 apparently healthy French middle-aged men and women, taken from the STANISLAS cohort. FIC was measured by a microparticular enzymatic immunoassay.

RESULTS

After a series of regression analyses involving 34 polymorphisms, FGB -455G/A was the only polymorphism that remained significantly associated with FIC when adjusting the analyses for multiple testing. Stepwise models showed that FGB polymorphism accounted for 4.39% of FIC variability in men. Additionally, interactions between FGB and with environmental factors (alcohol and smoking in men, and BMI in women) were found.

DISCUSSION

To our knowledge, this is the first study reporting an influence of FGB polymorphism on FIC in a healthy population. Our results concord with the already shown link between fibrinogen concentration and FIC, and support the hypothesis of a relationship between fibrinogen and endothelium in FIC homeostasis whose alteration may induce several metabolic disorders. The contribution of this gene, although modest, is consistent with the polygenic nature of insulin levels.

Age- and sex-related reference values for serum insulin concentration and its biological determinants in a French healthy population. The STANISLAS cohort

Insulin is involved in coronary heart disease through diabetes and metabolic syndrome. A great deal is known about insulin and its correlates, as well as factors related to changes in insulin. However, few studies consider the broad variety of correlates simultaneously. Therefore, the aims of the present study were to characterize the main factors of biological variation affecting serum insulin concentration and to establish reference limits of insulinemia in a presumably healthy French population. Insulin was measured using a microparticular enzymatic immunoassay. A total of 646 subjects aged 11–58 years from the STANISLAS cohort and divided into four groups of 162 males, 157 females, 163 boys and 164 girls, were included in the statistical analyses. In the whole population, serum insulin concentration varied from 0.80 to 54.60 µU/ml. Significant factors affecting insulin were age, gender, body mass index and glucose, in addition to alanine aminotransferase and high-density lipoprotein cholesterol in men, triglycerides and oral contraceptive use in women, and alkaline phosphatase in girls.

In summary, we presented biological correlates of insulin in both healthy French male and female adults and children/adolescents and determined reference limits for insulin for each group. These results will contribute to a better interpretation of insulin data in further studies and laboratory investigations.

Safety evaluation of modern oral contraceptives. Effects on lipoprotein and carbohydrate metabolism

An ideal oral contraceptive should either be neutral as regards metabolic risk markers for arterial disease or should only change them in directions that would be expected to reduce risk. Depending on their formulation, modern low dose oral contraceptives affect systems such as hemostasis, lipoprotein metabolism, and glucose and insulin metabolism. Some of these actions would be expected to decrease the risk of arterial disease and some might be expected to increase risk. Despite these associations there is at present no justification for widespread metabolic screening as a strategy to further improve oral contraceptive safety. Recent developments in atherosclerosis research support the introduction of progestogens such as desogestrel that allow the estrogenic increase in high density lipoprotein levels to persist and that may cause less of an elevation in plasma insulin responses to glucose. The predicted benefit of these formulations in terms of arterial disease is difficult to demonstrate in an epidemiological setting because of the rarity of the disease in young women.