Figure 1.

Unifying hypothesis linking the adverse effects of glitazones to induced testosterone deficiency. Testosterone, either directly or by conversion to dihydrotestosterone or oestradiol, all largely regulated by the effect of Sex Hormone Binding Globulin, acts on the Multipotent Stem Cell to promote differentiation to the progenitor cells for muscle, endothelium, bone, and red blood cells. By causing androgen deficiency, glitazones may reverse these effects and promote adipocyte production and action, with adverse clinical side-effects.