Discontinuation of metformin in type 2 diabetes patients treated with insulin.
BACKGROUND
Metformin added to insulin therapy in type 2 diabetic patients improves glycaemic control and decreases the required daily dose of insulin (DDI). Metformin should be discontinued if cardiac, hepatic or renal failure develops. We examined whether glycaemic control can be maintained after metformin cessation.


METHODS
We included 45 type 2 diabetic patients treated with insulin plus metformin, and 45 matched controls treated with insulin only. After discontinuation of metformin in the first group, we aimed for tight fasting and postprandial blood glucose levels, 4-7 and 4-10 mmol/l, respectively, in both groups. During 12 weeks we assessed glycaemic control every two weeks and, if necessary, adjusted the insulin dosage.


RESULTS
In the group in which metformin was discontinued, DDI increased from 67.9 +/- 22.9 to 92.2 +/- 29.4 IU (p < 0.001) leaving glycaemic control unchanged. In the controls, glycated haemoglobin (GHb) decreased by 0.93% (p < 0.001), while DDI increased slightly from 62.4 +/- 22.9 to 72.3 +/- 27.3 IU (p < 0.001). The increase in DDI was larger in patients in whom metformin was discontinued than in the controls (p < 0.001).


CONCLUSIONS
In type 2 diabetic patients treated with insulin plus metformin, glycaemic control can be maintained after discontinuation of metformin by increasing the DDI substantially (20 to 36%) during application of an intensified treatment protocol.
D001786:Blood Glucose / Q000378:metabolism; D016022:Case-Control Studies; D003924:Diabetes Mellitus, Type 2 / Q000188:drug therapy*; D005260:Female; D006801:Humans; D007004:Hypoglycemic Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D007328:Insulin / Q000008:administration & dosage / Q000627:therapeutic use*; D008297:Male; D008687:Metformin / Q000008:administration & dosage / Q000627:therapeutic use*; D008875:Middle Aged
D001786:Blood Glucose; D007004:Hypoglycemic Agents; D007328:Insulin; D008687:Metformin