Effect Of Probiotic Fermented Milk (kefir) On Glycemic Control And Lipid Profile In Type 2 Diabetic Patients: A Randomized Double-blind Placebo-controlled Clinical Trial
Notes for this study:
||Average fasting glucose decreased by around 20 mg/dL in the kefir group.
|Number of Subjects
||30-44, 45-64, 65+
This registered clinical trial compared fermented kefir to doogh, an Iranian drink made with yogurt, herbs and water. (Note: Although the study referred to doogh as the control, both of these drinks contain active bacterial cultures. However, doogh is an extremely common drink in Iran and may have been a part of all participants' regular diets.)
The doogh contained Streptococcus thermophilus and Lactobacillus bulgaricus, and the kefir drink contained Streptococcus thermophilus, Lactobacillus casei, Lactobacillus acidophilus and Bifidobacterium lactis. After eight weeks, the kefir group's fasting blood glucose was significantly lower than the doogh group's. No significant changes in lipid profiles were found.
The kefir group's serum HbA1C was also significantly lower than baseline, but HbA1C wasn't one of the trial's preregistered endpoints. Those were: lipid profiles, serum glucose and high-sensitivity C-reactive protein (hs-CRP). However, CRP isn't even mentioned in the published study.
A 2017 reanalysis of this data (https://doi.org/10.4183/aeb.2017.431) looked at two calculated measures of insulin resistance, _HOmeostatic Model Assessment for Insulin Resistance_ (HOMA-IR) and _Quantitative Insulin Sensitivity Check Index_ (QUICKI). The first analysis didn't report on insulin. This re-analysis reported no significant difference for insulin or QUICKI, but did find that HOMA-IR was significantly improved in the kefir group (though still well within diabetic range). Since the first analysis found a significant reduction in blood glucose for the kefir group, this isn't particularly surprising.
Note: The doogh and kefir used in this study were both commercially prepared, and the kefir contained very few species of probiotic bacteria. It didn't contain some of the most common kefir cultures, such as L. kefiranofaciens, the bacteria that typically produce kefiran and give kefir its body.