Effects of basal insulin on lipid profile compared to other classes of anti-hyperglycaemic agents in type 2 diabetic patients: a systemic review and meta-analysis of randomized controlled trials

Objective. Lipid profile represents an important driver of cardiovascular risk in type 2 diabetes. The effect of chronic insulin therapy on cholesterol levels is unclear. We aim to evaluate the effect of basal insulin on lipid profile compared to other classes of anti-hyperglycaemic agents in type 2 diabetic patients.

Research Design and Methods. We reviewed the literature for randomized controlled trials reporting changes of lipid parameters in type 2 diabetic patients randomized to basal insulin or other classes of anti-hyperglycaemic agents.

Results. Twenty-three studies were retrieved, reporting data on 14,133 type 2 diabetic patients. Basal insulin was glargine in the 78% of studies. The comparators were glucagon-like peptide-1 receptor agonists (GLP-1RA) in twelve studies, thiazolidinediones in five studies, dipeptidyl peptidase-4 inhibitors (DPP4-I) in three studies, and standard therapy (sulfonylurea ± metformin) in three studies. Heterogeneity was overall moderate and no publication bias was detected. The levels of total (TC) and LDL cholesterol (LDL-C) appeared to be significantly reduced by therapies with GLP-1 RAs in comparison to basal insulin, whereas no difference was detected between basal insulin and DPP-4 inhibitors or standard therapy. Thiazolidinediones produced a significant improvement in HDL cholesterol (HDL-C) but were associated with an increase in TC and LDL-C. Basal insulin was superior to standard therapy in triglyceride reduction.

Conclusion. GLP-1RA and thiazolidinediones were superior to basal insulin in the control of LDL-C and HDL-C, respectively. Combination of these two agents might be potentially helpful for the treatment of diabetic dyslipidemia, in addition to traditional lipid lowering therapies.