Effects of Lactulose on Gut Microbiota and Metabolism in Diabetic Constipated Patients

Inclusion criteria

• Age: 18-70 years
• Type 2 Diabetes Diagnosis (per 2017 ADA criteria), meeting ≥1 of:

• Fasting plasma glucose (FPG) ≥7.0 mmol/L
• hour plasma glucose ≥11.1 mmol/L during 75g anhydrous oral glucose tolerance test (OGTT)
• Random plasma glucose ≥11.1 mmol/L with hyperglycemia symptoms or hyperglycemic crisis
• Functional Constipation (Rome IV criteria), requiring:

• ≥2 of the following

• occurring in ≥25% of defecations
• Straining
• Lumpy/hard stools (Bristol Stool Scale 1-2)
• Sensation of incomplete evacuation
• Anorectal obstruction/blockage
• Manual maneuvers required
• <3 spontaneous bowel movements/week
• No loose stools without laxatives
• Exclusion of IBS diagnosis. Symptom duration >6 months, with active symptoms meeting criteria for last 3 months.
• Stable Glycemic Control: No anticipated antidiabetic medication adjustments during study
• Dietary Stability: Maintain consistent diet; avoid yogurt, fermented foods, prebiotic-containing processed foods, or other items that may confound results

Exclusion criteria

• Secondary Constipation due to organic diseases or medication effects.
• Constipation-predominant Irritable Bowel Syndrome (IBS-C).
• Concurrent gastrointestinal disorders (e.g., inflammatory bowel disease, colorectal cancer).
• Type 1 Diabetes Mellitus.
• Severe chronic comorbidities, including:

• Cardiopulmonary insufficiency
• Cerebrovascular diseases
• Psychiatric disorders
• Recent use (within 1 month) of confounding medications:

• Probiotics/prebiotics
• Antibiotics
• Laxatives (e.g., osmotic/stimulant agents)
• Prokinetics