I blogged a bit on this article in this months Journal of the American Academy of Dermatology when a pre-publication press release came out in January. The article looked at the relationship between the use of thiazolidinedione drugs for diabetes (such as actos) and psoriasis.
Looking at the massive UK General Practice Research Database they found a negative correlation between the use of these drugs and initial diagnosis of psoriasis - in other words they seem to protect against psoriasis
This is somewhat reminiscent of the beneficial side effect of simvastatin on psoriasis. While there is no clear-cut recommendation on the use of diabetes and cholesterol drugs in psoriasis, those psoriasis patients with diabetes or high lipids may want to make note of the medications out there which may offer dual benefits for them.