GCG and Alzheimer disease: In addition, 2 weeks after STZ injection, the level of insulin in the serum of WT mice was decreased comparing with nontreated WT mice (Fig. S1B), which was not seen in C57 that treated by STZ for 7 days, suggesting that the downregulation of insulin by STZ treatment is behind of the decrease of GIP, while the level of GLP1 was decreased in both WT and 3x Tg AD mice compared with their control groups, respectively (Fig. S1C).