Women with polycystic ovarian syndrome and elevated levels of insulin resistance are more prone to benefit from diets to improve insulin sensitivity: a meta-analysis

Abstract

Women with polycystic ovary syndrome (PCOS) are associated with increased levels of insulin resistance (IR). Most likely, IR is exacerbated by obesity, which is common, but not exclusive, with these women. Other than treatment with insulin-sensitizing drugs, specialized diets have also been implemented concurrently with drug treatments, as to reduce the patient’s weight. However, the capacity of certain diets, with respect to the level of IR, to reduce IR has not fully been explored. Therefore, we conducted a meta-analysis to determine in subjects with higher IR, if hypocaloric diets improve insulin sensitivity. Systematic review with a meta-analysis. PubMed, SCOPUS, EBSCO, and LILACS databases and retrieved studies' bibliographies were searched for prospective studies that investigated the association between diet and IR in PCOS until October 2018. Diet was defined as a modification of the patients’ nutrition intake according to caloric restriction, change in protein intake, or by using a specialized diet. IR measures (HOMA1-IR), pre- and post-intervention were extracted. Using Comprehensive meta-analysis software, depending on the level heterogeneity, determined by the ψ2-based Q-test and the I2-test, Fixed-Effects or Random-Effects models were used to calculate the pooled standard paired differences and standard error. No publication bias was detected by the Begg-Mazumdar's test and Egger's test. From 2,880 retrieved records, 21 publications (27 studies) fulfilled the inclusion criteria. Due to the heterogeneity of the diets, the random effects model was used. In 52% of studies, the diets led to a decrease of IR, where 30% had no effect. In 3 studies, the diet increased IR. Overall, the diets decreased IR (-0.53 ± 0.21, p<0.01). Subjects with high IR (HOMA1-IR>9) had a marked improvement (-1.28 ± 0.44, p<0.01). This was also determined with elevated IR (HOMA1-IR: 3.0-9.0; -0.68 ± 0.19, p<0.01). However, subjects with low IR (HOMA1-IR<3.0), diets did not improve IR (-0.13 ± 0.32, p=0.68). Here, we demonstrate that in subjects with higher IR, diets are more likely to improve IR in women with PCOS. Therefore, it is crucial to determine a subjects IR status before considering any intervention containing a diet.