I dont know if the insulin itself makes you put the weight on....I myself find if i give myself large doses of insulin for say a treat.....i do tend to put more weight on! but if i was to eat a small treat without insulin ( when at work) i dont tend to put anything on! also i have noticed big doses of insulin at night (even for a healthy snack) adds weight

so i dont do this any more!QUOTE]
yes it is. Insulin is a growth hormone and encourages fat. Hence why even if you are T1, you should still follow a healthy diet as eating the bad stuff means you inject more and then the weight goes on two-fold.
Eating snacks without injecting will raise your levels which results in unhealthy weight loss, as well as associated dangers of high blood sugar levels.