Higher blood glucose level associated with body mass index and gut microbiota in elderly people

Background: Some dominant bacterial divisions of the intestines have been linked to metabolic diseases such as overweight and diabetes. Objective: A pilot study aimed to evaluate the relations between the culturable intestinal bacteria with body mass index (BMI) and some principal cellular and metabolic markers of blood in people older than 65. Design: Altogether 38 generally healthy elderly people were recruited: ambulatory (n = 19) and orthopedic surgery (n = 19). Questionnaires on general health, anthropometric measurements, routine clinical and laboratory data, and quantitative composition of cultivable gut microbiota were performed. Results: Blood glucose level was positively correlated with BMI (r = 0.402; p = 0.014). Higher blood glucose level had negative correlation with relative share of intestinal anaerobic bacteria such as bacteroides (r = -0.434; p = 0.0076) and gram-positive anaerobic cocci (r = -0.364; p = 0.027). In contrast, the relative share of bifidobacteria (r = 0.383; p = 0.019) and staphylococci (r = 0.433; p = 0.008) was positively correlated to blood glucose level. In elderly people, a higher blood glucose concentration was predicted by the reduction of the anaerobes' proportion (adj. sex, age, and BMI R-2 = 0.192, p = 0.028) and that of Bacteroides sp. (adj. R-2 = 0.309, p = 0.016). Conclusion: A tight interplay between increased BMI, level of blood glucose, and the reduced proportion of cultivable bacteroides is taking place in the gut microbiota of elderly people.