A long-term, randomized, comparative study of insulin versus sulfonylurea therapy in type 2 diabetes

Abstract

Objectives: To study the effect of insulin and sulfonylurea (SU) therapy on glycaemic control, insulin resistance and cardiovascular risk factors in type 2 diabetic subjects.

Design: A prospective, parallel, randomized, controlled, long-term study.

Setting: Outpatient clinic in tertiary referral centre.

Subjects: Thirty-six type 2 diabetic subjects treated with diet and SU, aged 44-69 years and a duration of diabetes of between 2 and 14 years.

Interventions: Individually adjusted doses of insulin and glibenclamide.

Main outcome measures: Glycosylated haemoglobin (HbA1c), insulin resistance (euglycaemic glucose clamp), levels of lipids, lipoproteins and blood pressure.

Results: Glycaemic control improved during insulin treatment, but deteriorated on SU; HbA1c levels differed significantly between groups after 12 months of therapy (mean +/- SEM 7.9 +/- 0.3 vs. 9.5 +/- 0.4%, P = 0.004). Body mass index increased significantly during insulin treatment (26.4 +/- 0.7 to 27.8 +/- 0.7 kg/m2, P = 0.0001) and 30% of this increase was a result of an increase in lean body mass. The total glucose disposal rate showed a small increase in the insulin group. Levels of triglycerides and apolipoprotein B were significantly reduced during insulin treatment (1.8 +/- 0.2 to 1.5 +/- 0.2 mmol L-1, P = 0.03 and 1.58 +/- 0.1 to 1.40 +/- 0.08 g L-1, P = 0.003), and insulin prevented a reduction in the levels of high-density lipoprotein (HDL) cholesterol and apolipoprotein A-1 and an increase in Lp(a) lipoprotein observed in the SU group. Blood pressure levels did not change during therapy.

Conclusions: Insulin therapy was superior to SU treatment in achieving good metabolic control. Despite a modest improvement in cardiovascular risk factors in the insulin-treated group, no significant differences were observed between the groups after 1 year's treatment.