Yes it's 2 to 8, but below 2 and you're Golightly-ed.
See:
"Permitted Exposure Times For Various Temperature Ranges
Insulin preparations should not be exposed to temperatures between:
-20 to –10 degees C for more than 15 minutes
-10 to –5 degrees C for more than 30 minutes
-5 to +2 degrees C for more than 2 hours
8 to 15 degrees C for more than 96 hours
15 to 30 degrees C for more than 48 hours
30 to 40 degrees C for more than 6 hours
Insulin should never be stored above 40 degrees C.
It is important that insulin is never frozen, or exposed to a combination of high temperatures and excessive vibration.
Above table provided by Novo Nordisk"