Insulin resistance (IR) and compensatory hyperinsulinemia have been linked to conditions contributing to female infertility. The aim of this study was to investigate whether the Clinical Insulin Supressing (klinisk insulinsænkende, KISS) diet, which targets IR, improves the reproductive outcome of infertile women.
A retrospective study of infertile patients treated with either homologues semen (n=799) or donor semen (n=91) in Gynækologisk Klinik Taastrup (GKT) was performed. All patients had been prescribed the KISS diet. It was assumed that women who were hyperinsulinemic before the diet intervention were better responders than normoinsulinemic women. On the basis of this, it was hypothesized that women who became pregnant would have higher baseline C-peptide levels than women failing. In addition, the pregnancy rate in GKT for women inseminated with donor semen was compared to the national average reported by the National Danish Fertility Society. Confidence intervals (CIs) were computed and used to assess statistical significance. The spontaneous pregnancy rate for women treated with partner’s semen was also compared to rates from other sources.
There was no difference in baseline C-peptide levels between pregnant and non-pregnant women, neither in women treated with partner’s semen nor in women undergoing donor insemination (P>0.05). In women below 40 years of age who were inseminated with donor semen, the pregnancy rate in GKT and the national average appeared to be similar (12.3 % vs. 12.9 %). In women 40 years of age or above, the pregnancy rate in GKT of 14.9 % (95 % CI 7.4-25.7) was significantly higher than the national average of 5.7 % (95 % CI 4.8-6.7), as the CIs were not overlapping. The spontaneous pregnancy rate in women treated with husband’s semen in GKT was 33.3 %, which was higher than reported by other studies, but significance could not be tested. Since the KISS diet may be the main difference between GKT and other clinics, these findings may suggest that this diet improves the fertility treatment outcome, especially in women of advancing age.
A clear limitation to this study was the lack of an appropriate control group among others. Hence, the obtained results should be interpreted with caution. Randomized controlled trials, preferentially multicenter studies, are necessary in order to clarify the effect of the KISS diet on infertility.