Comparison of different insulin regimens in elderly patients with NIDDM

To compare the metabolic effects of three different frequently used regimens of insulin administration on blood glucose control and serum lipids, and the costs associated with this treatment, in subjects with NIDDM, who were poorly controlled with oral antihyperglycemic agents.

We studied 95 elderly patients with NIDDM (age 68 +/- 9 years, BMI 26.0 +/- 4.6 kg/m2, and median time since diagnosis of diabetes 9 years [range 1-37]; 37 men, 58 women), who were poorly controlled, despite diet and maximal doses of oral antihyperglycemic agents. Three insulin administration regimens were compared during a 6-month period: patients were randomized for treatment with a two-injection scheme (regimen A) or a combination of glibenclamide with one injection of NPH insulin, administered either at bedtime (regimen B) or before breakfast (regimen C), and insulin treatment was mainly instituted in an outpatient setting.

After 6 months of insulin treatment, fasting blood glucose of the total patient population had decreased from an average of 14.1 +/- 2.2 to 8.3 +/- 2.0 mmol/L (P < 0.001), and HbA1c fell from 11.0 +/- 1.3 to 8.3 +/- 1.2% (P < 0.001); 34 patients reached HbA1c levels below 8.0%, 25 of them even below 7.5%. With two insulin injections daily, HbA1c decreased from 11.2 +/- 1.3 to 8.2 +/- 1.2%, while during combined treatment, HbA1c fell from 10.5 +/- 1.2 to 8.1 +/- 1.1% (regimen B) and from 11.1 +/- 1.3 to 8.5 +/- 1.1% (regimen C). Comparable improvement of the other measures of glycemic control, lipids and lipoproteins, was observed in the different treatment regimens. Body weight increase was moderate (mean +/- 4.0 kg) and similar in all patient groups. One-third of patients starting with one insulin injection daily needed a second injection to control glycemia. One episode of severe hypoglycemia was observed. Combined insulin-sulfonylurea treatment was almost 20% more expensive than twice-daily administration of insulin alone.

Insulin treatment can safely be instituted in elderly patients with NIDDM. However, it is difficult to obtain optimal glycemic control. Insulin has moderate beneficial effects on serum lipoproteins. Although on the basis of glycemic control and weight gain, no preference for any treatment regimen can be discerned, twice-daily insulin administration is the most simple and cost-effective regimen.