The anti-diabetes drug pramlintide seems to be showing some promise in the treatment of Alzheimer's disease:

A new study has found treatment with the diabetes drug amylin (or pramlintide) safely improves learning and memory function in AD patients and reduces the AD pathology in their brains.

Read more at: https://medicalxpress.com/news/2017-03-diabetes-drug-safely-alzheimer-disease.html#jCp

This article focuses on amyloid, but another study suggests the drug helped reversed nitrotyrosine which could be significant as the nitration of tyrosine is a critical factor in Alzheimer's disease.

http://care.diabetesjournals.org/content/28/3/632

http://www.jneurosci.org/content/17/8/2653