I have just started on Lantus (this weekend), and immediately started to suffer from severe heartburn. It is possible that I have a hiatus hernia, but had very little in the way of symptoms prior to using Lantus. The effect was so bad last night that I was unable to sleep at all.
I have been on NPH Humulin and Humalog for 10 years, and Actrapid and Protophane for the 20 years prior to that.