Some people with Type 2 diabetes may gain weight after starting insulin therapy. Yes, this is true if people going in insulin do not cut the number of carbohydrates. This is because of improved blood glucose control. Uncontrolled diabetes causes people to lose weight because glucose cannot get to the cells in the body. When insulin is introduced, glucose can be absorbed from the carbohydrates eaten, leading to some of the weight that was previously lost being regained, but only if they do not reduce carbohydrates consumed.
Part of the reason behind the “negative image” of insulin is that physicians have historically used it as a warning to keep their patients motivated and focused on oral medication therapies. It’s no wonder that people who try their best, but inevitably need insulin therapy, often feel guilty. Another reason this is believed is that many people have known people with these complications that developed before insulin, but insulin therapy is all they can remember.