Review of management of type 2 diabetes mellitus

Commonly used drugs for type 2 diabetes are not ideal. The sulphonylureas, especially potent and long-acting agents such as glibenclamide, can induce hypoglycaemia, while metformin carries the risk of lactic acidosis.

To review the management of type 2 diabetes at the major teaching hospital in Tasmania, Australia, principally to determine the extent of use of glibenclamide and metformin in the elderly and patients where published contraindications are present.

A retrospective review of the medical records for 150 consecutive patients with type 2 diabetes admitted to the hospital in mid-1997, was performed. An extensive range of demographic and clinical variables was recorded for each patient. These included the duration of type 2 diabetes, the presence of other medical conditions, medication history, presence of any contraindications to the use of metformin or sulphonylureas, biochemical measures of diabetic control, and the presence of any diabetic complications.

The mean (+/-SD) age of the 150 patients included in the study was 70.1+/-11.8 years. The mean body mass index was 28.7+/-6.2 kg/m2 and the mean recent HbA1c level was 86+/-21%; only 24.7% of patients had a HbA1c level of 7% or lower. Of the 45 patients using glibenclamide, 40 (88.9%) had one or more risk factors for hypoglycaemia: over 65 years of age, renal impairment, or cognitive impairment and living alone. The study also found an extensive use of metformin in patients with contraindications and at highest risk of developing lactic acidosis. Sixty-six out of 70 patients (94%) using metformin had at least one contraindication according to the manufacturer's prescribing information, 57% of patients had two or three contraindications and 14% of patients had more than three contraindications. More than 20% of the patients had a renal function below published exclusion criteria.

There was evidence of over-utilization of metformin and glibenclamide in type 2 diabetes patients most at risk of adverse reactions. Insulin therapy could be a safer and more effective management strategy in many of these patients.