Metabolic inflexibility in women with polycystic ovary syndrome: a systematic review

Polycystic ovary syndrome (PCOS) is a risk factor for dysglycemia, insulin resistance, and type 2 Diabetes Mellitus (T2DM). Inefficient energy oxidation, metabolic inflexibility, is a marker of blunted metabolism. We conducted a systematic review on metabolic inflexibility in women with PCOS. We searched MEDLINE, EMBASE and Cochrane central (inception-October 2018) for studies evaluating metabolic inflexibility and reporting on changes in Respiratory Quotient (ΔRQ). We extracted data and assessed quality using The Newcastle–Ottawa Scale. We included five prospective cohort studies (461 women). Three compared PCOS women to unaffected subjects, one to women with obesity or T2DM, and one to adolescent girls; all had medium quality. Three studies showed higher metabolic inflexibility in women with PCOS (ΔRQ range 0.05–0.098) compared to unaffected subjects. Women with PCOS had similar metabolic inflexibility compared to those with T2DM (ΔRQ 0.05 ± 0.03 vs 0.06 ± 0.04, p =.98) and obesity (p =.06). Inflexibility was higher in hyperandrogenemic women with PCOS (ΔRQ 0.091 ± 0.060 vs 0.120 ± 0.010, p =.014). ΔRQ was lower in PCOS women with insulin resistance vs those with normal insulin sensitivity (0.04 ± 0.02 vs. 0.07 ± 0.04, p =.007). In conclusion, women with polycystic ovary syndrome appear to have higher metabolic inflexibility associated with hyperandrogenemia and insulin resistance.