Rethinking the Role of Constipation in Diabetes

Physicians may want to rethink the role of chronic constipation in diabetes management, say experts calling for more research in this area. Constipation has long been thought of as a benign condition and one better suited for self-management. It affects approximately 60% of patients with diabetes, up to 34% of the elderly in the general population, and 16% of adults overall.

Chronic constipation may be due to a number of factors, such as medications, metabolic abnormalities, and comorbidities, but also diet, a gut microbiota imbalance, or physiological factors such as anxiety.

But for patients with chronic medical conditions, such as diabetes, gastrointestinal complications can lead to more stress for individuals who are already managing a complicated condition. Constipation can be long-lasting, possibly leading to hemorrhoids, fecal impaction, bow­el incontinence, and gastrointestinal complications, such as diverticulitis, perforation, and peritonitis. Diabetes patients are at high risk for developing other colonic disorders beyond chronic constipation. These include enteropathic diarrhea, colorectal cancer, inflammatory bowel disease, microscopic colitis, and Clostridioides difficile (C diff).

Beyond the discomfort of constipation, new evidence shows an independent association with end-stage renal disease (ESRD), cardiovascular disease, Parkinson disease, and mortality.^3-7

A 2011 study published in the American Journal of Medicine by Elena Salmoirago-Blotcher, MD, of the University of Massachusetts Medical School, Worcester, found that of 93,676 postmenopausal women enrolled in the Women’s Health Initiative study, women with severe constipation had a 23% higher risk of cardiovascular events.⁷ Other studies have confirmed those findings, while a Japanese study by Honkura et al⁸ documented a 21 to 39% increase higher mortality associated with having only 1 to 2 bowel movements each week.

Constipation Has Been Overlooked and Understudied

The gut plays an important role in eliminating uremic toxins that are excreted by the kidneys to help regulate pH, but constipation may complicate and impede that process leading to excess morbidity and mortality, write the study authors of a review published in February 2020 in Kidney International Reports.

Led by Csaba P. Kovesdy, MD, FASN, a nephrologist and director of the Clinical Outcomes and Clinical Trials Program at the University of Tennessee Health Science Center, Memphis, the study authors say that constipation has been overlooked and understudied, particularly as a complication of chronic kidney disease.²

“In an ongoing quest to improve outcomes in chronic kidney disease, the time has come to advance our understanding of this overlooked, unpleasant, and hazardous gastrointestinal condition and to explore its therapeutic potential beyond conventional constipation management,” Kovesdy et al wrote.

The Problem With Diagnosing Constipation

Kovesdy et al suggests that constipation could be far more common among patients than physicians realize because instead of using subjective diagnostic tools, such as the Rome criteria and the Bristol Stool Form Scale, physicians may be relying on patients to self-report. Whereas diagnostic assessment tools can establish a baseline status and more details necessary for creating a comprehensive treatment plan.

Here’s a glimpse of the 2 most commonly used diagnostic tools for constipation:

· The Rome IV diagnostic criteria for functional constipation includes at least 2 of the following: straining during 25% of defecations; 25% of stools are lumpy or hard; feeling of incomplete evacuation 25% of the time; and a feeling of anorectal obstruction or blockage at least 25% of the time. The criteria also includes the absence of loose stools obtained only with the use of laxative.

· The Bristol Stool Form Scale includes 7 stool types:  type 1, separate hard lumps; type 2, sausage-shaped with lumps; type 3, resembling sausage or snake, but with surface cracks; type 4, smooth or soft sausage or snake; type 5, soft blobs with clear-cut edges; type 6, a mushy stool with fluffy pieces and ragged edges; and type 7, watery with no solid pieces.

Constipation can vary from normal-transit in which there is some straining and abdominal discomfort in the presence of an adequate bowel movement or slow-transit in which the bowels move, but slowly. There is a physiological explanation for slow bowel movements, per Kovesdy et al.

“Structurally, patients with slow-transit constipation have been shown to have reduced numbers of interstitial cells of Cajal (ICC) and myenteric plexus neurons expressing the excitatory neurotransmitter substance P54 and abnormalities in the inhibitory transmitters vasoactive intestinal peptide and nitric oxide,” the study authors wrote.