Its actrapid

Ok, you can gain weight when you first start insulin simply because your bloodsugarlevels are normal, and now your body processes carbs & calories like a person without diabetes. So you need to find the balance between exercise, diet and insulin.
If you know yourself & your diabetes so well that you are able to regulate this yourself thats good(didnīt mention how long it is since you were diagnosed with it and started on insulin) if not I would consult a docor whoever one gets help to this from where you live)
Did a quick search on some medical sites and found some groundrules(was easier than grabbing my textbook and copying everything

)
* Make sure your doctor has approved your exercise plan in advance! * Do not inject insulin immediately before exercise
* Do not inject insulin into large muscle groups you will be using during exercise - either use your tummy, or wait one hour after injecting into muscles
* Check your blood glucose before, during, and after exercise
* Have a carbohydrate snack before exercising
* Know that exercise burns glycogen from muscles and liver -- these glycogen stores will need to be replenished. Be sure to eat after working out!
* Be alert to nighttime lows after working out. When glycogen stores are depleted during exercise, your liver may rob glucose from your bloodstream causing lows up to 12 hours after exercising. Having a pre- and post-exercise snack can help avoid delayed hypoglycemia reactions.
* Do not work out close to bedtime.
* Do not work out in really hot weather. Hot weather can increase how fast insulin is absorbed and cause lows.
* Do not use saunas or hot tubs -- both can increase blood circulation and cause insulin to work faster in the body which may result in hypoglycemia (the same is true for hot baths after injecting insulin).