My A1C popped high, so I could get Shingrix 2 years before the nominal minimum age, paid for by insurance, on the technicality of having a T2D diagnosis. My blood sugar is much more under control now, but that's a nice little side benefit I won't hesitate to take advantage of. The most severe side effect for me was long term muscle pain near the injection site (even now 10 months after I got the shot). But it's totally worth it because the pain of shingles is far, far worse as I understand it.