Yes, this is interesting topic, indeed.
When I'd seen this article before you mentioned, I'd ignored this article because I thought it would be hard to conduct comparative effectiveness study for verapamil in type 1 DM.
To my knowledge number 1 indication of verapamil is atrial fibrillation (verapamil is not good for controlling BP, though some doctors still keep prescribing this medication for hypertension). Atrial fibrillation mainly affects senior population, whereas type 1 DM usually affects much younger population.
Because the onset of disease is so different in life time, I don't know how to design the study for validate effectiveness of verapamil in patients with type 1 DM in real-world.
I made simple cohort who used verapamil and had a history of type 1 diabetes mellitus.
@rohitv , do you have any idea for actual study design?
One possible design can be comparing glucose level before and after verapamil prescription on type 1 DM.