Our diabetologists have expressed doubt on the importance of HbA1c reports because, in my case, and that of many others, even if the blood sugar were higher than 200 mg/dl [11.1 mmol/L], the A1c would still be between 5.0 and 6.0. Why is this?

Since prolonged use of metformin can cause kidney damage, according to our doctor, is there another medication that is safer?

The glycosylated hemoglobin test, of which the hemoglobin A1c is also a type, is the standard test for the level of glucose exposure for patients with diabetes. Its measure remains an important element in the follow-up of this disorder. It has been shown that the results of this test mirror the average daily blood sugar over the last three months. However, there are some conditions which may cause this test to be inaccurate in predicting your average daily blood sugar. If you have a form of hemoglobinopathy that results in premature breakdown of red blood cells, this will decrease the circulation time of red blood cells and cause a falsely low test. Similarly, if you have a condition associated with premature breakdown of red blood cells from other causes, an artificial heart valve, liver disease, or kidney disease, this may also be the case. Since the hemoglobin A1c test is an average, it is important to know what your blood sugars are running throughout the day and night.

Metformin is a good drug and can be used chronically in patients with type 2 diabetes. However, it is contraindicated if you have kidney disease because it causes a build-up in the level of an organic acid called lactic acid that can make you sick. This only occurs if your kidneys don’t allow the drug to be cleared normally. Metformin does not cause kidney damage per se. I would recommend you talk with your physician more about your kidney function and how it affects your treatment with metformin. If you must go off metformin, and this is very clearly pointed out in the package insert, in terms of what the cutoff is for discontinuing use, then you need to talk of other strategies with your physicians. The choice of an agent is based on many things that involve an assessment of your overall health status and cannot be given as a single recommendation. There are other drugs that can be given by mouth before going on insulin. However, your physician is in the best position to make these recommendations.

JTL