To the best of our knowledge, data on the effects of synbiotic supplementation on markers of insulin metabolism and lipid concentrations in patients with gestational diabetes mellitus (GDM) are scarce. The aim of the current study was to determine the effects of synbiotic supplementation on markers of insulin metabolism and lipid profiles in GDM patients. In total, seventy patients with GDM aged 18–40 years were assigned to two groups – the synbiotic group (n 35) and the placebo group (n 35) – in this randomised, double-blind, placebo-controlled trial. Patients in the synbiotic group received a daily capsule that contained three viable and freeze-dried strains: Lactobacillus acidophilus, Lactobacillus casei and Bifidobacterium bifidum (2×109 colony-forming units/g each) plus 800 mg inulin for 6 weeks. Fasting blood samples were collected at the beginning and week 6 to quantify related markers. After 6 weeks of intervention, compared with the placebo, synbiotic supplementation led to a significant decrease in serum insulin levels (−1·5 (sd 5·9) v. +4·8 (sd 11·5) µIU/ml, P=0·005), homoeostatic model assessment for insulin resistance (−0·4 (sd 1·3) v. +1·1 (sd 2·7), P=0·003) and homoeostatic model assessment for β cell function (−5·1 (sd 24·2) v. +18·9 (sd 45·6), P=0·008) and a significant increase in quantitative insulin sensitivity check index (+0·01 (sd 0·01) v. −0·007 (sd 0·02), P=0·02). In addition, synbiotic intake significantly decreased serum TAG (−14·8 (sd 56·5) v. +30·4 (sd 37·8) mg/dl, P<0·001) and VLDL-cholesterol concentrations (−3·0 (sd 11·3) v. +6·1 (sd 7·6) mg/dl, P<0·001) compared with the placebo. Overall, the results of this study demonstrate that taking synbiotic supplements for 6 weeks among patients with GDM had beneficial effects on markers of insulin metabolism, TAG and VLDL-cholesterol concentrations.

To evaluate the effects of synbiotic supplementation on insulin resistance and lipid profile in individuals with the metabolic syndrome, we conducted a randomised, double-blind, placebo-controlled pilot study on thirty-eight subjects with the metabolic syndrome; they were supplemented with either synbiotic capsules containing 200 million of seven strains of friendly bacteria plus fructo-oligosaccharide or placebo capsules twice a day for 28 weeks. Both the synbiotic (G1) and the placebo (G2) groups were advised to follow an energy-balanced diet and physical activity recommendations. Parameters related to the metabolic syndrome and insulin resistance were measured every 7 weeks during the course of the study. After 28 weeks of treatment, the levels of fasting blood sugar and insulin resistance improved significantly in the G1 group (P< 0·001). Both the G1 and G2 groups exhibited significant reductions in TAG levels ( − 71·22 v. − 10·47 mg/dl ( − 0·80 v. − 0·12 mmol/l) respectively; P< 0·001) and total cholesterol levels ( − 21·93 v. − 14·2 mg/dl ( − 0·57 v. − 0·37 mmol/l) respectively; P= 0·01), as well as increases in HDL levels (+7·7 v. +0·05 mg/dl (+0·20 v. +>0·01 mmol/l) respectively; P< 0·001). The mean differences observed were greater in the G1 group. No significant changes were observed in LDL levels, waist circumference, BMI, metabolic equivalent of task and energy intake between the groups. The present results indicate that synbiotic supplementation increases the efficacy of diet therapy in the management of the metabolic syndrome and insulin resistance.