Högskolan i Skövde

Background: Type 2 diabetes mellitus is a metabolic disorder characterized by the rise of fasting plasma glucose from its normal range (≥125mg/dl). It is marked by insufficient production of insulin from pancreatic β-cells as a result of failed compensation due to insulin resistance. Several treatments are available for the disorder, which mainly focus on improving the sensitivity of insulin in different body tissues. Recently, probiotics were suggested as candidate treatments for type 2 diabetes and for extending lifespan as well. This experiment aims to investigate such claims using Drosophila melanogaster as a disease model.

Results: Other than the observed low average weights in treated larva samples, probiotics did not show any other significant results in affecting the length, glucose, glycogen, and trehalose levels (One-Way ANOVA and Kruskal-Wallis, p>0.05). Real-time PCR was only carried out once. Thus, no statistical tests were reliable enough to analyse the data obtained. The longevity study, on the other hand, did show significance (Log-rank (Mantel-Cox) test and Gehan-Breslow-Wilcoxon test, p<0.0001), as the probiotic Bifidobacterium lactis extended the lifespan of adult flies feeding on a high sugar diet significantly when compared to the control ones feeding on only high sugar diet without probiotics.

Conclusion: Except for weight measurements, none of the other results was reliable enough to make a concrete conclusion on whether the treatments indeed worked in reversing type 2 diabetes symptoms or not. Real-time PCR results did show some effects of some of the treatments at different developmental stages. However, unless Real-time PCR is repeated at least once using the same protocol, no deduction can be made. Additionally, the data obtained hint that the dosage used (0.025 g) was too high for larvae and adult flies and might have caused malnutrition by blocking their midgut and decreasing food absorption. Hence, false significant or non-significant results were acquired instead.

Further studies are required using a much lower probiotic dosage if Drosophila is used as a disease model. Although, other models such as mice or rats are recommended in this case, in order to reach a solid conclusion about the effectiveness of probiotics in treating type 2 diabetes mellitus. Baring these thoughts in mind and based on the results of this experiment, the null hypothesis indicating that there is no significant relationship between the use of probiotics and reversing type 2 diabetes mellitus symptoms is therefore accepted.