Hi Claire,
If you have glucose test strips for urine, then it may be worth letting your daughter wander about without a nappy until she pees and then test that. Not such great advice if you have carpets everywhere though, but possibly worth it for peace of mind - if her urine is negative then the chances of her being diabetic are much reduced. If positive then you need immediate medical help. It is quite black and white.
As Type 1 diabetics we have a higher chance of our children having Type 1 diabetes- this is a discussion on just that (discussing rates in the US, but I would assume the risks are pretty similar here). Note that it says "if the mother has type 1 diabetes and is age 25 or younger when the child is born, the risk is reduced to 1 in 25 (4 percent) and if the mother is over age 25, the risk drops to 1 in 100 — virtually the same as the average American."
http://www.joslin.org/info/genetics_and_diabetes.html
As to the vitamin d thing I'm a firm believer in this; you can redress the odds by giving vitamin d3; here is a link to a study discussing this.
http://housemajority.org/seaton/pdfs/27/5448201.pdf
Note that it says 'In children who received vitamin D supplementation regularly, the risk [of developing Type 1 diabetes]
was reduced by about 80% ] if the child had received at least the recommended dose compared with those receiving less.'
My underlining and bold.
The amount of vitamin d the children (from birth onwards) were given in the study was 2000 IU daily. The RDA in the UK is 400 IU for adults and 200 IU for children. I give my 3 1/2 year old 2000 IU a day and my 1 year old 1000 IU a day - he'll go up to full dose when he's 2 - there's no real reason other than parental caution as to why he isn't on the full 2000 IU's now though.
The vitamin d you want, by the way, is vitamin d3 in drop form - I buy mine from the US as bizarrely it's cheaper to do that than buy here. Drop me a line if you want more info.
Some people feel that vitamin supplementation is all a con and a way to extract more money from us, but I figure if there is evidence like that and the known toxicity levels for vitamin d are about 20,000 - 50,000 IU for several days then why on earth not? I discussed this with a GP friend of mine and he responded by putting all his children on vitamin d supplements!
In any event the NHS says that the under 5's are meant to be on vitamin d supplementation anyway; but I've never ever heard that from anyone at the NHS...
I hope however that this is all a false alarm and your daughter is fine.
All the best
Dillinger