Recently, my 53 year old sister, who has had type 2 diabetes for nearly two years treated with Lantus and Glucotrol, had a C-peptide level of 5.65 which I understand is very high. She says the doctor told her she doesn’t need to take insulin and probably won’t need to take it in the future. I have several questions:

Since she is on these medications, was the result higher than it would have been if she was on no diabetes medication, or just a pill?
Doesn’t the insulin level drop later on as the disease progresses?
How does the doctor know that she won’t need insulin in the future?
Do you know of people with type 2 who prefer to use insulin instead of taking pills?

Lantus does not directly affect C-peptide levels and the level of 5.6 (if it is in nanograms per milliliter) is within normal limits if it was measured in a non fasting state and only a little above normal for a fasting sample. This interpretation however needs to be checked against the normal levels in the laboratory that did the test.

What is important in choosing medication is to control blood sugars as acutely as possible as monitored by the quarterly hemoglobin A1c test. There would be no harm in trying too see if control could be maintained on oral hypoglycemic agents only, but using Lantus once a day by injection may work well. At the same time, it is quite probable that even if insulin can be dispensed with at present it may be needed later as residual insulin production wanes in the face of the continuing insulin resistance which is characteristic of type 2 diabetes.

DOB
Additional comments from Dr. David Schwartz:Lantus does not directly affect C-peptide levels and the level of 5.6 (if it is in nanograms per milliliter) is within normal limits if it was measured in a non fasting state and only a little above normal for a fasting sample. This interpretation however needs to be checked against the normal levels in the laboratory that did the test.

What is important in choosing medication is to control blood sugars as acutely as possible as monitored by the quarterly hemoglobin A1c test. There would be no harm in trying too see if control could be maintained on oral hypoglycemic agents only, but using Lantus once a day by injection may work well. At the same time, it is quite probable that even if insulin can be dispensed with at present it may be needed later as residual insulin production wanes in the face of the continuing insulin resistance which is characteristic of type 2 diabetes.

DS