Metabolism: Do artificial sweeteners increase diabetes risk?

The effect of non-caloric artificial sweeteners (NAS) on human metabolism is controversial. Some studies suggest that NAS may short-circuit metabolic pathways, resulting in consequences that range from increased obesity rates to higher cancer incidence. Scientists performed three experiments to assess the effects of NAS on blood glucose levels and glycemic index (a number that indicates the total rise in a person's blood glucose after ingesting a particular food) and how the host’s intestinal microbes modulate these effects.

Experiment 1

Scientists supplemented the drinking water of mice with high doses of saccharin, sucralose, or aspartame, all of which are commonly used NAS. Control groups of mice were given water only or water supplemented with glucose or sucrose solutions. After 11 weeks of exposure, glucose tolerance testing was performed on all groups of mice. The results are shown in Figure 1.

Figure 1 Glucose tolerance testing in experimental and control mice: blood glucose levels are shown per 15-30 minute interval following ingestion of oral glucose solution at t = 0; * and ** indicate significantly different results at p < .05 and p < .01, respectively

Scientists repeated the same experiment, but this time they separated each group of mice into two smaller groups and treated one group with antibiotic A and another with antibiotic B. Results are shown in Figure 2.

Figure 2 Glucose tolerance testing in groups of mice treated with antibiotic A or B; blood glucose levels are shown per 15-30 minute interval following ingestion of oral glucose solution at t = 0

Experiment 3

The scientists performed an additional experiment on two groups of mice that had never been exposed to NAS. One group of mice received an intestinal microbiota transplant from donor mice that drank saccharin solution. A second group received an intestinal microbiota transplant from donor mice that drank water only. The results of glucose tolerance testing for each group are shown in Figure 2.

Figure 3 Glucose tolerance testing following microbiota transplant from donor mice; blood glucose levels are shown per 15-30 minute interval following ingestion of oral glucose solution at t = 0; * and ** indicate significantly different results at p < .05 and p < .01, respectively.