Meanwhile, I have been troubled this last week or so by pain developing in both hips, not to mention big toes and thumb joints (not gout, according to analyses). It's worst when I get up and goes away gradually with movement. A few days ago I looked up 'sitagliptin arthritis' and discovered a case where a bloke who'd been on the former developed the latter after 6 months. Uh-huh. I'm on sitagliptin and PPI's so I did another search, for PPIs and arthritis, and came up with another gotcha. It seems that sitagliptin and PPIs together might be an excellent recipe for joint misery, especially since 'severe joint pain' is listed in sitagliptin's possible side-effects.
Anyway, two days ago I cut the sitagliptin (I'm still on metformin so no fear diabetic comas) and halved the dose of PPIs (and after-lunch espressi), and the pain is receding. I'll see my GP in a couple of weeks and negotiate a change of meds accordingly.