Hi BabyJane sorry been off MN most of today...
No, I don't have diabetes, but DP does (type 2). Diagnosis 6 months ago.
I thought I had diabetes about a year ago, so went to GP, who diagnosed anaemia from very heavy perimenopausal periods (I'm 48). One's periods are MEANT to get lighter and more infrequent, I'd always thought - but apparently I'm part of the unlucky minority who get heavier and more frequent 
. Anyway, I got a prescription and within weeks felt a million times better.
Moving ahead six months, DP is clearly not well. He went to GP - after severe nagging from me, with helpful remarks that what I'd thought was a lifechanging illness turned out to be crap periods and totally fixable.
GP arranged for him to have a fasting blood test first thing one morning later that week with the practice nurse. His symptoms at that point were tiredness, thirst and (my words) 'looking like death warmed up all the time'.
The blood test results came in at lunchtime, and he was called into the surgery later that day. This was because his results were way way over - 20+! GP immediately prescribed Metformin and handed him very strict diet sheet. Followup with specialist diabetes nurse two days later. He now sees the nurse every two weeks.
Since then he's been very virtuous with diet and drugs and is doing brilliantly. He looks ten years younger, we have a sex life again, and I've even discovered a way of making apple crumble that doesn't have sugar in it! Yes, he misses vast quantities of lager, ketchup, and marmalade but he's discovered that English beer is lovely and distinctly lower in sugar, Heinz make a perfectly decent sugar free ketchup, and sugar free marmalade tastes nicer than ordinary.
Best of luck at the GP's op.