Probiotics and Fibre Prevention and Treatment of Gestational Diabetes
by Dr. Sarah King ND
Upper Beach Health and Wellness
1937 Gerrard St E
Gestational diabetes (GDM) is a diagnosis that describes glucose intolerance with
the onset of diabetes during pregnancy in a previously nondiabetic woman. With
a prevalence of 8–18% in Canadian pregnancies, screening is recommended after
approximately 24 weeks gestation. It is also recognized that GDM occurs more often
in overweight and obese women, and is associated with an increased risk of multiple
complications in both mother and baby including preeclampsia, and the necessity
for a caesarian-section birth due to higher than normal-for-gestation birth weight.
Additionally concerning is that mothers with GDM have a 20–50% risk of developing
classical type 2 diabetes mellitus (T2DM) postpregnancy.
For the infant, having a mother diagnosed with GDM increases the risk of higher
than normal adiposity, shoulder dystocia, and neonatal hypoglycemia. It has been
postulated that a chronic low-grade inflammation may be a cofactor in obesity. This
coincides with the idea that maternal insulin resistance can lead to inflammation.
Although pharmaceutical preparations for glucose control exist, prevent is key as
short-term interventions may not reduce long-term complications in mother or infant.
When treating or preventing T2DM, combining diet and exercise has been known to
significantly improve blood glucose regulation and insulin sensitivity in nonpregnant
individuals. However, for pregnant women, there are mixed results with these lifestyle
and diet interventions, as compliance and consistency is typically more difficult.
Many studies have looked at the role of the gut microbiome in inflammation, T2DM,
insulin resistance, and weight gain. Multiple factors influence gut microflora including
antibiotic use (at any time from infancy onward) and current diet, with fibre intake
being increasingly beneficial.
Diet-based interventions have shown the greatest reduction in gestational weight gain,
lowering serum leptin levels by 20%. This can significantly affect glucose control and
insulin sensitivity, as well as potentially modify the low-grade inflammation we see in
overweight and obese patients. Additionally, researchers have been investigating the
role of probiotics as mediators of inflammation, and how this fits into the prevention
and treatment of GDM.
Probiotic Treatment for GDM
Probiotics work by altering the gut microbiome and modifying the concentration of
plasma lipopolysaccharides. Their presence in the gut, and the metabolites formed
by these probiotic bacteria, induces modifications in inflammatory pathways and affects
insulin sensitivity. In a 2016 study, Karamali suggested that certain strains of probiotics
may act by blocking the suppression of glucose transporter type 4 (GLUT4), and it may
be by this mechanism that we are able to influence glucose control.
One study by Luoto et al (2010) showed that probiotic supplementation in normal-weight
women during pregnancy was able to reduce the rate of GDM from 34% to 13%. Of
interest are the specific strains used in this study. Differing probiotic strains can have
different effects in the body, affecting distinctive pathways and showing improvements
in multiple areas of health. For example, we know that certain species and strains are
more beneficial for gas and colic, meanwhile others are better at preventing diarrhea
from antibiotic use. Similarly, not every supplemental probiotic strain will benefit insulin
sensitivity, appetite, and glucose control. Current research in this area shows just that.
Two studies by Lindsay et al (2014 and 2015) treated obese pregnant women, and
those newly diagnosed with GDM, with the strain Lactobacillus salivarius UCC118 at a
dose of 1 billion colony-forming units (CFU). In both cases, no beneficial effect was
reported in glycemic control, or other pregnancy outcomes. However, one outcome
was a reduction in total and LDL cholesterol, demonstrating benefit to lipid levels, but
not in reducing GDM status.
Karamali et al (2016) used 2 billion CFU of each Lactobacillus acidophilus and
Bifidobacterium bifidum in women who had been diagnosed with GDM, and found
benefit with this intervention within six weeks of treatment. Improvements were seen
in glycemic control, triglyceride levels, and VLDL concentrations. Additionally, there
were significant reductions in fasting blood glucose and serum insulin concentrations
when compared with placebo.
A 2015 study used a combination of four strains with 4 billion CFU per strain:
L. acidophilus LA-5, Bifidobacterium animalis lactis BB‑12, Streptococcus thermophilus
STY‑31, and Lactobacillus delbrueckii bulgaricus LBY‑27. After eight weeks of
intervention, women with a diagnosis of GDM presented with lower gestational weight
gain after probiotic treatment compared to placebo. The change was significant after six
weeks of intervention, and by the end of the study, the probiotic group had significantly
lower fasting blood glucose levels, and a decrease in insulin resistance of almost 7%.
One trend that seems to appear in research is the use and subsequent benefit of
Lactobacillus rhamnosus GG and Bifidobacterium lactis BB12 in GDM. The study
by Luoto (2010) used a dosage of 10 billion CFU for each of these strains, but other
combinations and dosages are also being investigated.
The SPRING study by Nitert et al (2013) in Australia has been set up to test the same
two strains as in Luoto’s 2010 study, but at a dose of 1 billion CFU for 24 weeks
during pregnancy, starting at 16 weeks of gestation. This study, once completed
and published, will shed light on whether these strains may be used in the prevention
of GDM in high-risk pregnancies among overweight and obese women. That said, a
Cochrane review published in 2014, without this data, concluded that when started
in early pregnancy, probiotic intervention reduced the rate of GDM as well as infant
birth weight. However, to date, there have been no reported differences in the rate of
miscarriage, stillbirth, or neonatal death.
Throughout several studies of probiotics in pregnancy, one thing that appears clear is
the safety profile of probiotic intervention of these tested strains. No significant adverse
effects have been reported to date on mother or offspring for probiotics, even with first
exposure during the first trimester.
Dietary Interventions and Fibre Intake
A meta-analysis of interventions for GDM showed dietary interventions were able to
reduce rates of GDM by 33%, but when probiotics were added with these dietary
changes/guidelines, the risk was reduced by 60%. As well, dietary interventions were
able to reduce the risk of gestational hypertension and pre-eclampsia by 84% and 34%,
Dietary interventions prepregnancy and continuing during gestation have the potential
for preventing GDM due to the ability to control glycemic load and gestational weight
gain. By adding 10 g of fibre daily, the risk of GDM is reduced by 25%.
The role of both fibre and beneficial probiotic species go hand-in-hand. The research
shows a benefit for both interventions on reducing the risk of GDM and improving insulin
sensitivity, but also, a high-fibre diet also contributes to the maintenance of a healthy
gut microbiome, as beneficial bacteria use fibre as a fuel source. This promotes their
survival and proliferation in the lower gastrointestinal tract.
Dietary fibre has many other benefits including delaying gastric emptying and slowing
glucose absorption, resulting in smaller increases in insulin levels. We know that
high-glycemic-load diets combined with low fibre intake increases the risk of GDM.
However, with any intervention or treatment, it’s important to keep the big picture in
Fibre intake, and possibly probiotic supplementation, both seem to benefit glucose
control in overweight and obese women, but all aspects of diet and lifestyle need to
be evaluated. Restricting carbohydrates and simple sugars to some degree will also
be helpful, but this needs to be properly calculated and monitored by a health-care
practitioner. Recommendations for glucose control in pregnancy restrict carbohydrates
to 35–40% of daily calories, though this calculation may vary slightly depending on
For example, multiple studies have shown the benefit of mild to moderate physical
activity preconception and during pregnancy. One study of daily stair-climbing showed
a decreased risk of GDM by 49–78% when compared to non–stair-climbers. From
a safety aspect, no adverse effects have been reported on the health of the mother or
fetus in pregnant women who participate in mild to moderate physical activity during
Although diet and lifestyle modifications have the ability to modify glucose control and
prevent GDM, major changes in dietary habits may be difficult for pregnant women to
follow consistently. Of important note during the first trimester would be to emphasize a
fibre-rich diet, while restricting simple carbohydrates.
Probiotic supplementation may serve as an additional or alternative treatment while
continuing counselling on diet and physical activity. To date, several probiotic strains
and combinations have shown benefit in modifying glucose regulation. Among
them are species such as Lactobacillus rhamnosus, Bifidobacterium animalis lactis,
Bifidobacterium bifidum, and Lactobacillus acidophilus, though others are still being