Cordain L, Eades MR, Eades MD. Hyperinsulinemic diseases of civilization: more than just syndrome X. Comp Biochem Physiol Part A 2003;136:95-112.
Compensatory hyperinsulinemia stemming from peripheral insulin resistance is a well recognized metabolic disturbance that is at the root cause of diseases and maladies of Syndrome X (hypertension, type 2 diabetes, dyslipidemia, coronary artery disease, obesity, abnormal glucose tolerance). Abnormalities of fibrinolysis and hyperuricaemia also appear to be members of the cluster of illnesses comprising Syndrome X. Insulin is a well established growth promoting hormone, and recent evidence indicates that hyperinsulinemia causes a shift in a number of endocrine pathways that may favor unregulated tissue growth leading to additional illnesses. Specifically, hyperinsulinemia elevates serum concentrations of free insulin like growth factor 1 (IGF-1) and androgens while simultaneously reducing insulin like growth factor binding protein 3 (IGFBP-3) and sex hormone binding globulin (SHBG). Since IGFBP-3 is a ligand for the nuclear retinoid X receptor ?, insulin mediated reductions in IGFBP-3 may also influence transcription of anti-proliferative genes normally activated by the body’s endogenous retinoids. These endocrine shifts alter cellular proliferation and growth in a variety of tissues whose clinical course may promote acne, early menarche, certain epithelial cell carcinomas, increased stature, myopia, cutaneous papillomas (skin tags), acanthosis nigricans, polycystic ovary syndrome (PCOS) and male vertex balding. Consequently, these illnesses and conditions may, in part, have hyperinsulinemia at their root cause and therefore should be classified among the diseases of Syndrome X.