Objective: Polycystic ovaries are a common ultrasound finding, yet few of these women have many clinical features of polycystic ovary syndrome. Clinical presentation may relate to degree of insulin resistance, common polymorphism at the insulin gene VNTR, and birth weight. We therefore examined the relationship between insulin sensitivity, insulin gene VNTR genotype, birth weight and presence of polycystic ovaries/features of polycystic ovary syndrome in a normal population study.
Design and patients: In 224 young women recruited as normal volunteers, ovarian morphology was determined by transabdominal ultrasound and features of polycystic ovary syndrome were identified on clinical and biochemical examination. Insulin sensitivity was estimated from fasting glucose and insulin levels using the homeostasis model. Insulin gene VNTR genotypes were determined in women and their parents.
Measurements and results: Thirty-three per cent (74/224) had polycystic ovaries on ultrasound. These women had higher birth weights (P = 0.004), higher insulin sensitivity (P = 0.02) and higher leptin levels for body mass index (P = 0.04) than women with normal ovaries. However among women with polycystic ovaries, increasing severity of clinical phenotype (based on number of features of: menstrual irregularity, acne, hirsutism, serum testosterone > 3 mmol/l and LH > 10 IU/l) was associated with decreasing insulin sensitivity (P < 0.0001) and related to paternally transmitted insulin gene VNTR class III alleles (P = 0.03).
Conclusion: Women with polycystic ovaries on ultrasound have increased insulin sensitivity and possible leptin resistance, which could predispose to future weight gain. However, in these women the appearance of clinical features of polycystic ovary syndrome is related to insulin resistance and insulin gene VNTR class III alleles.