Diabetes Type 2 Support Group
Type 2 Diabetes is a condition in which the body either does not produce enough insulin or does not make efficient use of it. Insulin is a hormone needed to convert food into glucose, a sugar that the body uses for energy. Without enough insulin, glucose can accumulate in the blood, and can cause serious health problems such as heart disease and strokes and organ damage...

It depends on your situation. If 40 units is what you need to stay in control, that is your number. Only your Doc can help you there.
I know some folks do take more than you do. Are you having any problems with it?
I take lantus and have for a year. I started out on 18 units a night. At that amount I was having some lows into the 60's, so gradually decreased it to 10 units. My Dr. encourages me to do my own adjusting. I've noticed when sick the numbers go up and then I just use more units. I recently had surgery of renal cell carcinoma and taking 16 units as b/g was in the high 300's. It will settle down again, with hopes of getting off it in the future. Hope this helped in some small way.....but we are all different.
Ali