Q: I have had type-2 diabetes for the last 10 years. I was taking metformin twice a day and everything was pretty well controlled, but my doctor dropped it due to kidney issues. He put me on Januvia, but my hemoglobin A1C jumped from 6.3 to 8.2. Now I also have to take Lantus insulin in the morning. I am a 65 year old male with good eating habits and I walk regularly. Why would I have to stop taking metformin if it was working? Is there anything else I can do to manage my blood sugar?
A: The kidneys are one of the body’s vital organ systems that can be affected by diabetes. The job of the kidneys is to serve as a “filter” for the blood: they eliminate impurities by sending them out through the urine while keeping the healthy stuff in the bloodstream. Years of elevated blood sugar can cause damage to the kidneys. It’s not unusual for patients with T2 DM to have kidney problems – they often don’t know they have had diabetes for a number of years, during which time the high blood sugar can damage the kidneys, the back of the eyes, and/or the nerves. In addition, other medical conditions that can affect the kidneys, like hypertension (high blood pressure), are also present. The end result? The millions of tiny filters in the kidneys that are supposed to keep the blood clean are unable to do so.
When this happens, it is necessary to avoid medications that are eliminated from the body by the kidneys - metformin is one of those. When a person with impaired kidney function takes metformin, it can build up to dangerous levels and actually do more harm than good. A life-threatening condition called “lactic acidosis” has been seen in people with impaired kidney function who take metformin. Januvia, on the other hand, can be taken at normal doses as long as kidney problems are mild. When kidney disease becomes more severe, the dose of Januvia should also be reduced.
In most cases when kidney function is no longer normal and blood sugar levels are above target, insulin is the best option. Insulin is the most potent and effective treatment for high blood sugar – and its dose can be adjusted more precisely. Most patients adjust their dose of Lantus based on the level of their fasting blood sugar (the blood sugar level when you first get up, before breakfast).
At this point, it is more important than ever that you control your blood sugar levels very tightly so that your kidney problems do not worsen. Research has shown that lowering both blood sugar and blood pressure towards normal levels can slow, or possibly halt, the progression of kidney disease. Certain types of blood pressure medicines may be more effective than others in helping preserve kidney function in patients with diabetes. Smoking should definitely be avoided, too.
It is never too late to improve your situation. Do whatever it takes to control your blood sugar as well as possible. Ask your doctor about how to adjust your dose of Lantus, and whether rapid-acting insulin at mealtimes might be beneficial. Make sure your blood pressure is in a good range. Discuss your diet with a registered dietitian, and consider taking your exercise program up a notch. Despite the fact that diabetic complications have begun to occur, you still have a great deal of say in regards to your future health.
If you have a question about diabetes care that might be of interest to the readers of this column, please e-mail it to firstname.lastname@example.org. Dr. Hirsch cannot comment on individual medical cases.
Laurence J. Hirsch, MD
Dr Hirsch graduated from the University of Rochester
He is board-certified in Internal Medicine and in Endocrinology/Metabolism.
Prior to joining BD, he was Assistant Professor of Medicine at Northwestern University, and spent