A man sitting on a grey couch clutching his stomach.
A common complication of diabetes mellitus is digestive problems, which can pose as diarrhea or constipation.

What Are the Common Complications of Diabetes Mellitus?

Diabetes mellitus is a condition that affects how the body makes and uses the hormone insulin. Insulin helps cells to take up glucose (sugar) molecules from the blood to use as energy. If there is not enough insulin or cells cannot use it effectively, glucose levels increase, causing high blood sugar. This is one of the key features of diabetes. Over time, high blood sugar can damage structures such as blood vessels and nerves, leading to various complications. This article explores the 10 most common complications of diabetes mellitus and how to prevent them.

What is Diabetes Mellitus?

There are two main types of diabetes mellitus: type 1 and type 2.

In type 1 diabetes, the body stops producing insulin. Therefore, glucose molecules cannot enter cells, so they accumulate in the blood instead. People with type 1 diabetes need to use insulin injections to control their blood sugar and avoid complications.

In type 2 diabetes, cells become less sensitive to insulin’s effects, a phenomenon known as insulin resistance. They body may also produce less insulin than is necessary to keep the blood sugar under control. Some people manage type 2 diabetes by making dietary and lifestyle adjustments. Others require medication, and in some cases insulin injections are necessary.

Although the causes of type 1 and type 2 diabetes are different, the symptoms are similar. They include:

  • Increased thirst.
  • Frequent urination.
  • Increased hunger.
  • Weight loss.
  • Fatigue.
  • Irritability.
  • Chemicals called ketones in the urine.

Diabetes mellitus can also cause several long-term complications, which we will discuss in detail below.

10 Most Common Complications of Diabetes Mellitus

1. Increased Risk of Heart Disease and Strokes

Having diabetes doubles the risk of developing cardiovascular disease, including heart attacks and strokes. This is because high blood sugar damages the blood vessels over time. Diabetes is also often associated with other cardiovascular disease risk factors, such as high blood pressure and high cholesterol.

It is a significant problem since there may be no obvious symptoms until a serious cardiovascular event occurs. Therefore, it is essential that people with diabetes have regular blood pressure and cholesterol checks to monitor their condition. Another important test is the A1C (or HbA1C) test. It tells doctors about their patient’s average blood sugar levels over the past three months.

Lifestyle choices, such as being physically active, eating healthy food and stopping smoking can also help to reduce the risk of cardiovascular disease.

2. Nerve Damage

If high blood sugar affects the blood vessels that supply the nerves, it can cause serious nerve damage (neuropathy).

Peripheral neuropathy is one of the most common forms of nerve damage. It usually starts in the toes or fingers and gradually works its way up the body. It can cause symptoms such as numbness, tingling or pain.

Some people also develop autonomic neuropathy. It affects the nerves responsible for digestion, bladder function, sweating and more.

Diabetic amyotrophy is a rare form of nerve damage that causes pain in the hip and thigh.
Maintaining healthy blood sugar levels is the best way to prevent or slow nerve damage. Monitoring one’s glucose regularly, eating the right foods at the right time and taking medication correctly will all help.

3. Digestive Problems

Autonomic neuropathy can affect the nerves that supply the gastrointestinal tract and cause numerous digestive problems.

For example, if the nerves that supply the stomach are damaged, it might empty more slowly than normal, causing nausea and discomfort. It can also make it more difficult to manage glucose levels effectively.
Meanwhile, damage to the nerves that supply the intestines can cause diarrhea or constipation.

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4. Eye Problems

Diabetic retinopathy occurs when high blood sugar damages the retina. The retina is a structure at the back of the eye that converts light into nerve signals to send to the brain.

Retinopathy can cause visual disturbances, such as blurring, loss of night vision, or sensitivity to bright lights. It can also cause blindness if it is not treated quickly enough.

People with diabetes also have a higher-than-average risk of developing other eye problems, like glaucoma or cataracts. Therefore, it is essential to attend regular eye exams so that any issues can be detected and treated early.

5. Foot Problems

Nerve damage in the feet causes loss of sensation, meaning that injuries can easily be missed. Furthermore, damaged blood vessels can make healing slow, increasing the risk of infections.

If left untreated, these infections can develop into ulcers or gangrene. In severe cases, amputation may be necessary to stop the infection from spreading.

People with diabetes should check their feet daily and report any problems to their healthcare provider. It is also advisable to have a professional foot exam at least once a year.

6. Sexual Dysfunction

Damage to the nerves and blood vessels that supply the genitals can cause sexual dysfunction in both men and women. Men may find it difficult to get and maintain an erection, while women might experience decreased arousal.

7. Kidney Disease

High blood sugar and blood pressure can damage the kidneys over time, leading to a condition known as nephropathy. This makes it difficult for the body to remove extra fluids and waste products in urine.
There may be no symptoms in the early stages, but severe nephropathy can cause swelling in the feet and lower legs. It can also make it harder to control blood pressure.

The best way to reduce the risk is by keeping blood sugar and blood pressure under control. Doctors should also monitor kidney function by checking the urine and blood regularly.

8. Increased Risk of Infections

High blood sugar provides the perfect environment for microorganisms, like bacteria and fungi, to breed. Therefore, people with diabetes have an increased risk of infections, including skin, gum, vaginal and urinary infections.

It is important to report any symptoms, such as rashes or dental problems, promptly to prevent them from becoming serious.

9. Increased Risk of Dementia

There appears to be a link between diabetes and dementia, including Alzheimer’s disease. The exact reason for this is unknown but it seems that the risk increases significantly with poor blood glucose control. Therefore, managing one’s blood sugar should help to reduce the risk.

10. Depression

People with diabetes also have a high risk of depression, especially if they are living with other complications.

Some people can manage their mood by engaging in therapy or making lifestyle changes. Others may require medication. Affected individuals should discuss their symptoms with a healthcare provider to create a personalized treatment plan.