I have type 2 diabetes and take novalog and lantus (insulin glargine). do these insulins actually cause weight gain?

Weight gain: Yes, weight gain can occur with Insulin therapy, including Lantus (insulin glargine) and novalog, and has been attributed to the anabolic effects of Insulin and the decrease in glucosuria.

Maybe: If your diabetes is not controlled prior to using Insulin expect to gain a few pounds as your diabetes is intensified. Drugs such as metformin, liraglutide, canagliflizin, and pramlintide used in combination with Insulin can minimize wt gain.