Making lightweight

Cutting back on carbs will decrease your need for insulin and will make you lose weight at the same time. You will most likely go through and adjustment period where you need to fiddle with your insulin as you are cutting back on carbs (food in general) and up your activity level. Hypos could occur more often but after a couple of weeks you should get the hang of it.

On the losing 6 kg part ... it really depends on your current BF%, as i'm assuming that's what you want to lose. If you're already skinny or even around 10-12% losing that 6 kg will be more challenging, Basically the higher your current BF the "easier" it is. I've lost about 5 kg in six months and am currently around 7-8% BF, which for me is a bit hard to sustain, around 10% for me is easier to sustain. When you first start out exercising again a good tip i can give you is to measure certain circumferences (belly, upper arms, chest, shoulders) as you will most likely put on some muscle and lose some fat so the scale is not the best device for measuring progress in the beginning.