Insulin resistance parameters in users of the injectable contraceptive depot medroxyprogesterone acetate during one year of use.

Objectives: The aim of the study was to assess insulin resistance parameters using successive homeostasis model assessment (HOMA) and clinical evaluations in healthy new users of depot medroxyprogesterone acetate (DMPA).

Methods: A prospective 12-month study was carried out to compare 31 DMPA users with 25 copper intrauterine device (Cu-IUD; TCu380A) users, matched for age (± 1 year) and body mass index (BMI; ± 1 kg/m(2)). Participants met the following criteria: age 18 to 40 years, BMI < 30 kg/m(2), fasting glucose < 5.5 mmol/l, 2-h glucose after a 75 g oral glucose load < 140 mg/dl. BMI, waist circumference, fasting glucose, fasting insulin and HOMA of insulin resistance (HOMA-IR) were evaluated at baseline and after 6 and 12 months of contraceptive use. Insulin resistance was defined as a HOMA-IR value > 2.7.

Results: The DMPA group showed significant increases in BMI, waist circumference, fasting insulin and HOMA-IR throughout the observation period in relation to baseline. Significant increases in BMI and waist circumference were observed in the DMPA group at 12 months compared with the Cu-IUD group. Five DMPA users had abnormal HOMA-IR values, three of whom had gained > 5 kg in weight at 12 months.

Conclusions: HOMA-IR represents a useful tool to indicate changes in carbohydrate metabolism in non-obese DMPA users, especially when accompanied by measurement of clinical parameters such as BMI and waist circumference.