I'm T2, and climbed Kili 18 months ago.
I'm a lo-carber, but I have to admit, on days when I felt really bad, Haribo sweets (the soft jelly type) were an absolute god send!
Drinking water is super important. I had a camel pack - but found that it was actually quite hard to suck the water through the long straw. Keep a bottle of water handy - because you won't be able to get water into your body fast enough, and sucking it through a straw is just not efficient enough!
I didn't make it to the top - I got to Barafu Hut (4,600m) just short of Stella Point and Uhura Peak (5,700m/5,895m). Altitude sickness can hit you hard, and I also ended up with what might have been pulmonary edema (Fluid on the lungs!).
I really can't comment on insulin, though...
Best of luck to you. It is an amazing experience that you will not regret!