Probiotics, especially synbiotics (probiotics combined with fiber), are very important for pregnant women with gestational diabetes. Results of a study published in the British Journal of Nutrition demonstrated that Lactobacilus acidophilus, L.casei and Bifidobacterium bifidum together with inulin lowered insulin levels, as well as low-density lipoprotein cholesterol and triglycerides in pregnant women after just 6 weeks of use. 
The study included 70 patients – women aged 18-40 with diagnosed gestational diabetes. Over the course of six weeks half of the subjects were given a supplement of Lactobacillus acidophilus, Lactobacillus casei and Bifidobacterium bifidum (2×109/ g of each strain) together with 800 mg inulin. After six weeks their insulin metabolism improved significantly (insulin levels and insulin resistance (HOMA index) was reduced, the function of insulin producing pancreatic β –cells and insulin sensitivity improved significantly). The subjects supplementing synbiotics had significantly lower blood lipids – the level of triglycerides fell, as did the concentration of low-density lipoprotein cholesterol. The results of this study show that 6 weeks of synbiotic supplementation improved insulin metabolism and concentration of triglycerides and low-density lipoprotein cholesterol in patients with gestational diabetes.
Ahmadi S, Jamilian M, et al. The effects of synbiotic supplementation on markers of insulin metabolism and lipid profiles in gestational diabetes: a randomised, double-blind, placebo-controlled trial. Br J Nutr. 2016 Sep 29:1-8.