To reduce the pain caused by subcutaneous injections, microneedle patches as the new transdermal drug delivery method are gaining increased attention. In this study, we fabricated a composite insulin-loaded microneedle patch. Silk fibroin, a natural polymer material, was used as the raw material. The tip of the microneedle had good dissolving property and was able to dissolve rapidly to promote the release of insulin. The pedestal had the property of swelling without dissolving and was carrying insulin as a drug store. The insulin carried by the pedestal could release continuously through the micropore channels created by the microneedles. This kind of microneedle could achieve a sustained release effect. It was observed that the insulin had good storage stability in this kind of microneedle, and it maintained more than 90% of its biological activity after 30 days. The results of transdermal delivery to diabetic rats showed that the microneedle patches displayed an apparent hypoglycemic effect and indicated a sustained release effect. These drug-loaded silk microneedle patches may act as potential delivery systems for the treatment of diabetes.