To the Editor: We read with interest the recent article on insulin resistance,1 and we strongly support the argument that there is no current clinical utility to measuring fasting insulin levels. However, we are concerned about the statement that “otherwise well patients whom we see in practice are demanding (and receiving) metformin, or are being told they need it, particularly for polycystic ovary syndrome” (PCOS). Therapy in PCOS targets symptoms. Although Samaras et al imply that metformin is not required in “well patients”,1 the “well patient” is not defined. Most women with PCOS are, by definition, symptomatic, and most benefit from therapy.
We contend that, although measurement of insulin levels is not justified, insulin resistance is established in PCOS, and metformin is an effective treatment for women with PCOS. This contention is well supported in the literature. It is recognised that most women with PCOS have insulin resistance leading to hyperinsulinaemia and that insulin resistance plays a central aetiological role in the clinical manifestations of PCOS.2
However, as outlined by Samaras et al,1 the insulin level is not an appropriate marker for insulin resistance (a challenging parameter to measure in routine clinical practice) and, consequently, insulin resistance is not included in the diagnostic criteria for PCOS.
Strategies to decrease insulin resistance have proven effective in studies where patients are selected based on clinical diagnostic criteria for PCOS, not insulin levels. Indeed, reducing insulin resistance with both lifestyle change3 and insulin sensitisers4 is emerging as a promising treatment strategy.2 Although not yet “approved” for treating PCOS in Australia, metformin is an effective treatment for anovulatory cycles and infertility, and induces a mild decline in hyperandrogenaemia. This is supported by a recent Cochrane review.4,5 Increasingly, metformin is recommended as a first- or second-line therapy in anovulatory infertility4,6 because, in contrast to conventional infertility therapies, it does not increase multiple pregnancy rates.
