The impact of testosterone administration to female-to-male transsexuals on insulin resistance and lipid parameters compared with women with polycystic ovary syndrome.

Objective: To evaluate the impact of testosterone (T) administration to female-to-male transsexuals (FtMs) on insulin resistance and lipid parameters and to compare the effects with women with polycystic ovary syndrome (PCOS).

Design: Cohort analysis.

Setting: University hospital.

Patient(s): Twenty-nine FtMs and 240 women with PCOS.

Intervention(s): Screening panel, ultrasound of the ovaries, hormone, lipid, and glucose and insulin measurements.

Main Outcome Measure(s): Endocrine, metabolic parameters, and insulin resistance.

Result(s): The PCOS women had significantly higher fasting, 1-h, and 2-h insulin levels and a significantly lower insulin sensitivity index compared with FtMs before and after their T treatment. There were higher triglyceride levels and lower high-density lipoprotein cholesterol levels upon T treatment in FtMs compared with the PCOS women. Women with PCOS had higher body mass index (BMI) values. Positive correlations between insulin resistance indices and BMI were found only in women with PCOS.

Conclusion(s): Testosterone administration by itself showed little detrimental influence on insulin resistance indices, but it had significant effects on lipid profiles. Compared with T, BMI had a greater impact on insulin resistance in women with PCOS.