Other complications of diabetes mellitus

Due to their serious consequences and their clear relationship with hyperglycaemia, the best known complications of diabetes are retinopathy, nephropathy, neuropathy and macrovascular disease. However, a great number of less-known complications seriously impede quality of life for diabetes patients. With the use of improved glucose-lowering medications, the risk of infections has dropped but diabetes patients are still about 20% more likely to get an infectious disease compared to healthy individuals. Connective tissue disorders are another main source of discomfort and can lead to prolonged disability. Ultimately, diabetes will lead to dysfunction in almost any tissue, and diabetes patients can be considered at increased risk for almost any disorder that is the result of the chronic wear and tear of daily life.


It was already noted by Joslin and colleagues that 'with proper treatment, the response of the diabetic to infection approaches the normal'. However, hyperglycaemia is a risk factor for infections, and the inflammatory response to an infection decreases insulin sensitivity and aggravates hyperglycaemia. Since many diabetes patients will go through periods of hyperglycaemia, they remain at a slightly increased risk of infection. Some infections are commonly associated with diabetes. The excess sugar in the urine creates a fertile environment for bacteria and yeasts, and therefore urogenital infections occur frequently, also as a presenting symptom of newly diagnosed diabetes. Likewise, superficial skin infections followed by deeper connective tissue and bone infections are a feared complication in the setting of diabetic foot ulcers. However, many other infections threaten the patient with diabetes including rare infections such as mucormycosis.

Connective Tissue disorders

Chronic hyperglycaemia will damage almost any tissue and this is most notable in the myriad of connective tissue disorders that affect diabetes patients. These are frequently attributed to aging rather than to diabetes. Aging is indeed important but diabetes could be said to lead to accelerated aging of these tissues. Clinically, this usually presents as low-grade inflammation or loss of elasticity in the affected tissue.

Diabetes and oral hygiene

Diabetes patients are more prone to have periodontitis, and periodontitis had been associated with poor glycaemic control. Whether improved dental care will improve diabetes control has not been definitively settled, but clearly improved dental care is a worthy goal in itself.

Dead-in-bed syndrome

This syndrome, where a patient is unexpectedly found dead in an undisturbed bed at a relatively young age, is fortunately rare, but its cause remains a mystery. Both hypoglycaemia and (pre-existing?) cardiac conduction disturbances have been suggested to play a role, but conclusive evidence is lacking.

Hearing impairment

Thought to be due to a combination of neuropathy and vasculopathy, sensorineural hearing loss is more frequent in both type 1 and type 2 diabetes.


  1. Frits Holleman Written by the moderator
    Frits Holleman (Moderator) added a on 21 January 2015 at 11:56AM
    Dear Albie, thanks for your comment, and point well taken. Indeed it is often hard to distinguish the effect of high glucose from some of the confounders such as high insulin. I have now changed 'hyperglycemia' to 'diabetes' to more adequately reflect your point.
  2. no profile image
    Albie Cilliers added a suggestion on 4 December 2014 at 10:47AM
    I would really like to see the specific references/study that prove without a doubt your statement "high glucose will lead to dysfunction in almost any tissue", ie the high glucose on its own, and not other factors like low insulin, or insulin insensitivity, or other factors.
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