We performed a questionnaire interview study among the patients who visited a diabetes clinic in a general hospital. The study was conducted over 18 months to survey the prevalence of GI symptoms in patients with diabetes. Outpatients with impaired fasting glucose diagnosed by an oral glucose tolerance test or diabetes mellitus were recruited and interviewed regarding their gastrointestinal symptoms. The exclusion criteria were patients 1) who refused to participate in the interview or produced an incomplete questionnaire, 2) with severe illness or mental illness, 3) who were pregnant, or 4) had a past abdominal surgery history except for appendectomy or hernia repair surgery. Written informed consent was obtained from all subjects before enrollment. This study was approved by the Institutional Review Board (IRB).
Functional gastrointestinal disorder criteria
There are many subgroups of functional gastrointestinal disorders (FGIDs) in the ROME III classification. We investigated the prevalence of functional dyspepsia, irritable bowel syndrome, and functional constipation using ROME III criteria in the study patients. We also investigated the prevalence of functional gastrointestinal disorders in the presence of diabetes complications. The ROME III criteria classify functional dyspepsia into two subtypes, epigastric pain syndrome (EPS) and postprandial distress syndrome (PDS), so we followed this classification. Irritable bowel syndrome (IBS) was stratified into three different subtypes according to bowel habits, IBS with constipation (IBS-C), IBS with diarrhea (IBS-D), and IBS with mixed bowel habit and unclassified IBS (IBS-M or U). Upper GI symptoms and bowel habit symptoms were also surveyed using a questionnaire. We asked about the upper GI symptoms of early satiation and postprandial fullness in reference to functional dyspepsia in the ROME III consensus. The questionnaires for bowel symptoms followed the ROME III consensus of functional constipation.
The questionnaire on gastrointestinal symptoms manufactured by the Rome Foundation was translated into Korean by the Korean Society of Neurogastroenterology and Motility. A total of 45 questions categorized the symptoms into three diagnosis categories of functional dyspepsia, IBS, and constipation based on the Rome III criteria. Trained interviewers conducted the survey in the outpatient department.
The patients were given a specific questionnaire that evaluated the frequency and severity of functional dyspepsia. Early satiation, postprandial fullness, epigastric pain, epigastric burning sensation, epigastric bloating, and nausea symptoms were graded from 1 to 5 (1: absent, 2: mild, 3: moderate, 4: severe, and 5: very severe). The frequency of the symptoms was graded from 1 to 5 (1: never, 2: less than one day per month, 3: about two or three days per month, 4: at least one day per week, 5: at least several times per week, and 6: almost every day). In the functional dyspepsia diagnostic questionnaires of other studies including ROME III, severity was not specifically addressed, so we made our own cutoff value.[9, 10] However, we determined the PDS and EPS subgroups in agreement with the ROME III criteria. The functional dyspepsia patients were classified into the PDS subgroup if they responded that they experienced postprandial fullness and/or early satiation at least several times per week. The EPS subgroup included the patients who reported epigastric pain at least once per week.
The questionnaire responses were used to divide the IBS group based upon the ROME III criteria. The IBS disorder group was categorized further into three subgroups according to the bowel patterns at a particular point in time.[11, 12] The frequency of recurrent abdominal pain or discomfort was scored. The Bristol stool form scale was used to divide the stool aspect to categorize the IBS subgroups.
Straining, lumpy or hard stools, the sensation of anorectal incomplete evacuation, the sensation of anorectal obstruction/blockage, manual maneuvers to facilitate defecation, and fewer than three defecations per week were investigated through the questionnaire. If two of these were satisfied, the patients were assigned to the functional constipation group according to the ROME III criteria. The prevalence of each symptom was also investigated.
Among the patients with diabetes, tests for evaluating autonomic neuropathy were conducted in the endocrinology clinic by trained technicians. In addition, the HbA1c level in each patient was evaluated. Three tests were conducted, the Valsalva ratio test, the expiration/inspiration (E/I) ratio test, and the blood pressure (BP) response to standing test. And if any of the test results were abnormal, autonomic neuropathy was diagnosed. Prediabetes was diagnosed by a fasting glucose level of 100 – 125 mg/dl or an HbA1c level of 5.7 – 6.4%.
To analyze prevalence, crosstabs were used. Binodal logistic regression analysis was used to assess the association of each Rome III subgroup with diabetic neuropathy after adjusting for age and sex. All results were considered to be significant if the P-value was less than 0.05. SPSS version 18 (SPSS Inc., Chicago, IL, USA) was used for the statistical analyses.