Fig. 1

Short and long-term metabolic characterization of DMO after insulin treatments. a Body weight was reduced in DMO at P1 (**p < 0.01 vs. Control), P7 (**p < 0.01 vs. Control) and 5 weeks (**p < 0.01 vs. rest of the groups) while differnces were no longer observed and 10 weeks of age (p = 0.146). b Glucose levels (mg/dl) were reduced at P1 (**p < 0.01 vs. Control) and no further differences were detectable P7 (p = 0.171), 5 weeks (p = 0.424) and 10 weeks (p = 0.158). c Insulin levels (ng/ml) were slighly reduced at P1 and P7 although differences did not reach statiscital sifnificance (p = 0.064 and p = 0.077). No differences were observed in insulin levels at 5 (p = 0.716) or 10 weeks (p = 0.451) (P1 Control n = 6 and SZT n = 4; P7 Control n = 7 and STZ n = 9; 5 weeks Control n = 15, Control + ICV-Ins n = 8, Control + IN-Ins n = 8, STZ n = 8, STZ + ICV-Ins n = 6 and STZ + IN-Ins n = 7; 10 weeks Control n = 27, Control + ICV-Ins n = 17, Control + IN-Ins n = 8, STZ n = 18, STZ + ICV-Ins n = 10 and STZ + IN-Ins n = 6). d GTT measured as AUC was signifcantly reduced in DMO (% Control) (**p < 0.01 vs. rest of the groups) (Control n = 13, Control + ICV-Ins n = 8, Control + IN-Ins n = 6, STZ n = 13, STZ + ICV-Ins n = 8 and STZ + IN-Ins n = 5). e Plasma insulin levels during GTT were not affected at time 0 (p = 0.866), while insulin treatment significantly increased insulin levels at time 15 (**p < 0.01 vs. rest of the groups, ††p < 0.01 vs. Control + IN-Ins) (Control n = 13, Control + ICV-Ins n = 7, Control + IN-Ins n = 6, STZ n = 13, STZ + ICV-Ins n = 8 and STZ + IN-Ins n = 5). Student t-test for independent samples was used when 2 populations were under study (P1 and P7) and one-way ANOVA, followed by Tuckey b or Tamhane test, was used when 6 groups were under study (5 and 10 weeks). f Central insulin levels were increased in the brain after IN and ICV administration. g Experimental timeline including all groups under study