Rosiglitazone Plus Insulin For Type 1 Improves Glycemic Control, BP Without Increasing Insulin Needs
“Rosiglitazone in combination with insulin resulted in improved glycemic control and blood pressure without an increase in insulin requirements, compared with insulin- and placebo-treated subjects. "Because insulin sensitizers have been effective in improving blood glucose control in type 2 diabetic individuals, for whom insulin resistance is a prevailing feature, it seems reasonable to consider the possibility that these agents would be of benefit in overweight subjects with type 1 diabetes, who are more likely to have a degree of insulin resistance," write Suzanne M. Strowig, MSN, RN, and Philip Raskin, MD, from the University of Texas Southwestern Medical Center at Dallas. "This study was designed to examine the safety and efficacy of the thiazolidinedione rosiglitazone in the treatment of overweight adults with type 1 diabetes."
In a double-blind fashion, 50 adult study subjects with type 1 DM with a baseline body mass index (BMI) of 27 kg/m2 or more were randomized to receive either insulin and placebo or insulin and 4 mg of rosiglitazone twice daily, for eight months. In all study subjects, insulin regimen and dosage were adjusted to produce near-normal glycemic control.
Both groups had a reduction in hemoglobin A1c (HbA1c) level (rosiglitazone: 7.9% to 6.9% ; placebo: 7.7% to 7.0% ) and weight gain (rosiglitazone: 97.2 to 100.6; placebo: 96.4 to 99.1).
In the rosiglitazone group but not in the placebo group, baseline measures of BMI, total daily insulin dose, total cholesterol, high-density lipoprotein (HDL) cholesterol, and low-density lipoprotein (LDL) cholesterol were predictors of improvement in HbA1c level. Total daily insulin dose increased in the placebo group (74.0 ± 33.8 to 82.0 ± 48.9 units; for baseline vs week 32), whereas it decreased slightly in the rosiglitazone group (77.5 ± 28.6 to 75.3 ± 33.1 units).
In the rosiglitazone group, blood pressure (BP) improved (systolic, 137.4 vs 128.8 Hg, baseline vs week 32; diastolic, 87.2 vs 79.4 mmHg). Incidences of hypoglycemia were similar for both groups.
"Rosiglitazone in combination with insulin resulted in improved glycemic control and blood pressure without an increase in insulin requirements, compared with insulin- and placebo-treated subjects, whose improved glycemic control required an 11% increase in insulin dose," the authors write. "Weight gain and hypoglycemia were similar in both groups at the end of the study. The greatest effect of rosiglitazone occurred in subjects with more pronounced markers of insulin resistance."
The authors note potential risks for hypoglycemia, edema, and anemia with rosiglitazone.
"Treatment with rosiglitazone should only be considered after efforts at improving glycemic control with intensive insulin treatment, increased blood glucose self-monitoring, and dietary management do not result in desired glycemic goals," they conclude. "More investigation into the long-term effects of rosiglitazone may provide more definitive evidence regarding the beneficial impact of rosiglitazone on glycemic control and cardiovascular risk factors in type 1 diabetic individuals who have features of insulin resistance."
Diabetes Care. 2005;28:1562-1567