Effects of progestin-only long-acting contraception on metabolic markers in obese women.

BACKGROUND: The metabolic effects of progestin-only long-acting reversible contraception [levonorgestrel-releasing intrauterine system (LNG-IUS) and etonogestrel implant (ENG-I)] have been studied in normal-weight women but not in obese [body mass index≥30kg/m(2)] women.

STUDY DESIGN: A nonrandomized open-label prospective trial of healthy obese, reproductive-age women desiring to use long-acting reversible contraception (LARC) or nonhormonal contraception (NHC). At baseline, 3 months and 6 months, homeostasis model assessment insulin resistant (HOMA-IR) score, insulin sensitivity (HOMA-%S) and β-cell function (HOMA-%B) were calculated based on fasting insulin and glucose values. In addition, components of metabolic syndrome [fasting glucose (FG), high density lipoprotein cholesterol and triglycerides, systolic and diastolic blood pressure, abdominal circumference] were measured. Twenty-four subjects total (8 in each arm) were needed to detect a 1.0 difference in HOMA-IR with 80% power and a two-sided alpha of 0.05.

RESULTS: We present data on eight NHC, eight ENG-I and nine levonorgestrel intrauterine system (LNG-IUS) users. FG increased, and insulin sensitivity decreased over time among ENG-I users to a greater extent than among LNG-IUS users when compared to women using a nonhormonal method [FG change over 6 months=9.4mg/dL, 4.6mg/dL and -2.1mg/dL, respectively; p=.01); (HOMA-%S change over 6 months=-29.9%, -14.8% and 19.3%, respectively; p=.02)], while β-cell function and insulin resistance did not change significantly (p>.05).

CONCLUSION: While changes in FG and insulin sensitivity were seen in the present study among obese progestin-only contraceptive users, either progestin-only LARC method may be safely used clinically.