Adverse effects on carbohydrate and lipid metabolism

It is widely known that hormonal contraceptives( HCs) use can lead to an impairment of carbohydrate and lipid metabolism which are important risk factors for cardiovascular diseases.

These effects occur with progestin-only contraceptives as well as with contraceptives containing estrogens. HCs may interfere with glucose metabolism, in part by creating an effect of peripheral insulin resistance and in part by diminishing the insulin-secreting capacities of the islets of Langerhans. It is shown that deterioration of glucose tolerance in the 1st trimester of oral contraceptives use is due to the synthetic estrogen, while hyperinsulinism after 6th month of use is due to the progestin component.

The early deterioration of glucose tolerance could be due to a direct action of estrogen on the pancreas, where specific estrogen receptors have been identified. The reduction of glucose levels by estrogen is due to reduction of glucogenolysis with an increase of hepatic gluconeogenesis.

These effects may be explained by the action of estrogens on insulin and glucagon: estrogen inhibit the secretion of glucagon On the other hand, progestins augment insulin and glucagon secretion without modifying their ratio in the portal vein ^(1,2). Hyperinsulinism is observed in women using combined hormonal contraceptives(COC) or progestins only, whether or not there is a deterioration of glucose tolerance.

This effect which can appear after 3 months of use, continues as long as HCs are used. The determinations of insulin secretion are more reliable if peptide C in plasma is determined, as it is released by the pancreas in an equimolar amount with insulin and is not retained by the liver. The hyperinsulinism is due to a hypersecretion and not to a diminution in degradation of insulin. So, probable pill-induced insulin resistance is comparable to that of pregnancy^(1,2,3).

Although all progestins used in contraception, potentially, induce insulin resistance with hyperinsulinism, the effect seems to be largely dependent on the type of progestin used and are more marked with 19 nortestosterone derivatives than with 17 alpha hydroxy proge sterone, because of the structural similarity of 19 norsteroids ⁽⁴⁾. The most notable changes seem are seen with Levonorgestrel (LNG), mono or triphasic, and are minimal with the low-dose COC containing third-generation progestins (desogestrel and gestodene) ^(5,6,7).
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In fact, was reported that women taking triphasic combined oral contraceptives develop, after three months from the start of the treatment ,a significant increase of the plasma glucose concentration and the plasma insulin response to oral glucose. While, fasting plasma cholesterol ,HDL-cholesterol and LDL- cholesterol concentrations did not change as compared with baseline values, nor did the ratio of total cholesterol to HDL-cholesterol. While plasma triglyceride levels increased significantly. The effects of HCs on serum lipid levels depend on the dose of estrogen and dose and type of progestin.