I've also recently been put on Glic, started with 30mg per day, but had no effect, raised to 60mg, started to have an effect within a couple of days, but still get overnight spikes, so have been put Linagliptin, which doesn't to be doing anything. However, on the advice of others (including Andy12345) I have reduced my carb intake and eliminated starchy carbs completely from evening meals. Has made a big difference. Still get spike overnight but they have a lower starting point.
Andy