The main concern I would have about the addition to Lantus 20 units daily would be the risk of low blood sugar, especially in combination with
glimepiride. Both Lantus and glimepiride can cause low blood sugar or hypoglycemia. Just make sure you're watching for the signs of low blood sugar, which are, sudden headache, feeling shaky, and weakness. There are many more signs of hypoglycemia and I encourage you to research it more yourself.