Methane intestinal production and poor metabolic control in type I diabetes complicated by autonomic neuropathy.

Aim: At the state of art it's unknown the correlation between diabetes and lower gastrointestinal disorders. Some studies show a significantly higher prevalence of small intestinal bacterial overgrowth in patients with type I diabetes in particular complicated by autonomic neuropathy. No data exists about gastrointestinal methane production in patients with diabetes and autonomic diabetic neuropathy. The aim of this paper was to evaluate the correlation of small intestinal bacterial overgrowth and gastrointestinal methane production with metabolic control and daily insulin requirements in patients with type 1 diabetes and. autonomic diabetic neuropathy.
Methods: Thirty subjects with type 1 diabetes and autonomic diabetic neuropathy were underwent hydrogen and methane lactulose breath test (LBT) to evaluate the presence of small intestinal bacterial overgrowth (double peak of hydrogen) and methane production. The metabolic control was evaluated through the glycated hemoglobin and the daily insulin requirement (calculated as ratio between total insulin units in a day and body weight). Methane producers were treated with metronidazole (500 mg bid for 10 days) and perform a LBT 8 weeks after the end of therapy
Results: Eight over thirty patients (26.6%) met the diagnostic criteria for small intestinal bacterial overgrowth. 11/30 patients (36%) were methane-producers (mean baseline value 16.37 ± 13.01 ppm; mean peak 26.62 ± 11.41 ppm); interestingly this subset of patients showed a worse glycemic control (mean HbA1c 8.16 ± 0.9% vs. 7.49 ± 0.8%, P<0.05). After metronidazole therapy 7/11 (63.3%) reduced CH4 production and they showed a mean HbA1c significantly lower than corresponding value before antibiotic therapy (7.63 ± 0.7% vs. 8.25 ± 0.8%).
Conclusion: Our study showed for the first time a possible role of CH4 production in metabolic control. In particular, the most interesting data is that an increased values of HbA1c seems to be related to a gut CH4 production as confirmed by its significant improvement after eradication therapy. We are not yet able to determine whether poor glycemic control is the cause or the consequence of the selection of methanogenic flora.