A randomized-controlled clinical trial investigating the effect of omega-3 fatty acids and vitamin E co-supplementation on markers of insulin metabolism and lipid profiles in gestational diabetes

Background: Limited data are available that evaluated the effects of combined omega-3 fatty acids and vitamin E supplementation on glucose homeostasis parameters and lipid concentrations in gestational diabetes (GDM).

Objectives: The present study was designed to determine the effects of omega-3 fatty acids and vitamin E co-supplementation on glucose homeostasis parameters and lipid concentrations among women with GDM who were not on oral hypoglycemic agents.

Methods: This prospective randomized, double-blind, placebo-controlled clinical trial was carried out among 60 patients with GDM. Patients were randomly allocated to take either 1000-mg omega-3 fatty acids from flaxseed oil plus 400-IU vitamin E supplements (n = 30) or placebo (n = 30) for 6 weeks. Fasting blood samples were obtained from at the beginning of the study and after 6-week intervention to quantify related variables.

Results: After 6 weeks of intervention, changes in fasting plasma glucose (-11.8 ± 11.0 vs +1.5 ± 11.9 mg/dL, P < .001), serum insulin concentrations (-1.8 ± 6.9 vs +5.8 ± 12.1 μIU/mL, P = .004), homeostasis model of assessment-estimated insulin resistance (-0.8 ± 1.6 vs +1.4 ± 2.8, P = .001), homeostasis model of assessment-estimated beta cell function (-0.2 ± 27.7 vs +22.8 ± 48.2, P = .02), and quantitative insulin sensitivity check index (+0.01 ± 0.02 vs -0.01 ± 0.02, P = .01) in the omega-3 fatty acids plus vitamin E group were significantly different from the changes in these indicators in the placebo group. Changes in serum triglycerides (+10.8 ± 41.5 vs +34.2 ± 35.5 mg/dL, P = .02), VLDL-cholesterol (+2.1 ± 8.3 vs +6.8 ± 7.1 mg/dL, P = .02), low-density lipoprotein (LDL)-cholesterol (+11.6 ± 18.8 vs +1.7 ± 15.9 mg/dL, P = .03) and HDL-cholesterol concentrations (+1.9 ± 8.7 vs -2.4 ± 7.7 mg/dL, P = .04) were significantly different between the supplemented women and placebo group. However, after controlling for baseline total cholesterol levels, maternal age, and BMI at baseline, the changes in serum LDL-cholesterol concentrations were not significantly different between the 2 groups. We did not find any significant effect of joint omega-3 fatty acids and vitamin E supplementation on total cholesterol concentrations.

Conclusions: Overall, we demonstrated that omega-3 fatty acids and vitamin E co-supplementation in GDM women had beneficial effects on glucose homeostasis parameters, serum triglycerides, VLDL-cholesterol, and HDL-cholesterol concentrations, but it did not influence total-cholesterol and LDL-cholesterol levels.