Hello,
levels of 400+ are alarming and could be you at risk of diabetic coma caused by diabetic
ketosis. No, these meds are not sufficient under such case. Insulin should be used. You need immediate treatment in this case.
To manage blood sugars you need medication (probably insulin) combined with low carb diet and exercise. Do not eat sweets, breads, rice, candies, fruit, fruit juice when your sugars are so high.