Chronic diarrhoea and diabetes mellitus: Prevalence of small intestinal bacterial overgrowth

The mechanisms of chronic diarrhoea, a frequent symptom in diabetes mellitu s, are multifactorial and complex, although small intestinal bacterial over growth and autonomic neuropathy seem to play a major role. This study evalu ated the prevalence of small intestinal bacterial overgrowth and the effect s of antibiotic treatment in a population of diabetic patients with chronic diarrhoea (defined as > 3 stools/24 h, weight > 200 g/24 h, duration > 3 w eeks). Small intestinal bacterial overgrowth syndrome was diagnosed by gluc ose-hydrogen breath testing (sensitivity:78 %, specificity:89 %). The chara cteristics of diarrhoea (duration, number of stools per day, and gastrointe stinal symptoms) were noted. Autonomic neuropathy was assessed by cardiac p arasympathetic tests. A total of 35 patients were included, 15 with small i ntestinal bacterial overgrowth syndrome (43 %, group 1) and 20 with no bact erial overgrowth (group 2). Age (52.9 +/- 13.5 vs. 53.9 +/- 11.8 years, NS) , duration of diabetes (13.8 +/- 9.1 vs. 10.6 +/- 7.8 years, NS), and HbA(1 c) level (10 +/- 2.9 vs. 10.9 +/- 2.4 %, NS)were not different between the two groups. In group 1, duration of diarrhoea was longer (18.1 +/- 18.5 vs. 7.75 +/- 4.02 months, P = 0.05), the number of stools higher (7.1 +/- 5.7 vs. 4.6 +/- 2.6/24h, P <0.05), and gastrointestinal symptoms more frequent (13 vs. 10, P <0.05). The prevalence of small intestinal bacterial over gro wth syndrome and gastrointestinal symptoms was not different in patients wi th and without autonomic neuropathy (9 vs. 8 and 12 vs. 11 respectively, NS ). Eight patients with bacterial overgrowth received antibiotics (amoxicill in-clavulanic acid, 1.5 g/24h for 10 days). Dramatic clinical improvement w as observed in 6 out of 8 of these patients. It is concluded that small int estinal bacterial overgrowth should be considered in case of chronic diabet ic diarrhoea because of its frequency (43 %), facility of diagnosis, and of ten successful treatment with antibiotics.