Do not dive with the pump, even in a drysuit. It will be about a $5,000.00 mistake!!! Because you will have to buy another pump because it will break!.
Also you don't dive with the pump on at all. The pump sends insulin into the body which reduces your blood sugar. A drop in blood sugar means hypoglycemic issues. It is FAR safer to be "hyper" glycemic (high blood sugar) when diving. Your brain and body will still function with a high blood sugar but when your sugar drops, and it usually hits fast and hard, you can not think correctly, you get fast heartbeats, hyperventalation, sweats, shakey feeling (sometime uncontrollably) and underwater you can DIE when this happens. I Never dive unless my blood sugar is in the 180 - 200 BGL range. I know DAN (divers alert network) has a guideline to not dive if sugar is below 150 or 180 BGL.
Also as a side note, usually insulin dependant diabeties is far safer, when diving, than diabetics that rely on a pill. As a pill's half life fluctuates in its effectiveness where injected insulin's half life is extremely predictable. What this means is better control. Lets say I check my blood sugar and it's 210 bgl (high) and I take a pill, I really don't know exactly how much the pill is going to help drop my sugar. I might go ahead and dive but the pill drops it too much and I start to have a hypoglycemic conditon, I just don't know. However, if I take an insulin injection, using a sliding scale for 210bgl I know that it take exactly X units of insulin to bring my sugar down to say 100bgl. This is what I mean by better control.
Jeremy