Insulin Degludec precautions. Do not use this medication when you have low blood sugar (hypoglycemia). Before using this medication, tell your doctor or pharmacist your medical history, especially of: kidney disease, liver disease. You may experience blurred vision, dizziness, or drowsiness due to extremely low or high blood sugar. Do not drive, use machinery, or do any activity that requires alertness or clear vision until you are sure you can perform such activities safely.