Sorry to hear about Ted. I hope things are coming on okay? It may be Old News but there's been research on using metformin to prevent laminitis in horses (appears most useful beforehand though - which makes it tricky to know when to start!) I'm not sure if vets are ready to go with this yet or if it needs more trials. Anyway it's something to keep an eye on for the future. Your experience makes me feel twitchy about my (tubby) horse!
The effect of metformin on measurements of insulin...[Equine Vet J. 2008] - PubMed Result
Metformin looks like being useful on pre-diabetic humans.