Secondary Diabetes- Causes, Symptoms, Diagnosis, and Treatment

What Is Secondary Diabetes?

Diabetes mellitus is a group of metabolic disorders characterized by a high blood sugar level over a prolonged period. The body uses glucose from the blood as fuel for various activities. Insulin is the principal hormone made by the pancreas (beta cells of the pancreas) that regulates the uptake of glucose from the blood into most of the cells in the body. The deficiency of insulin or the inability of the body cells to utilize them is the major cause of all forms of diabetes mellitus. Secondary diabetes is diabetes that results as a consequence of any other endocrine disorders, genetic disorders, or medication.

What Conditions Can Lead To Secondary Diabetes?

Secondary diabetes can develop due to,

1. Diseases of the pancreas destroy the pancreatic beta cells, which produce insulin. For example-

• Hemochromatosis - It is a disorder in which extra iron builds up in the body. They can sometimes damage the pancreatic beta cells and cause insulin deficiency.

• Pancreatitis - It is the inflammation of the pancreas, which in turn affects the amount of insulin the body produces.

• Cystic Fibrosis - It is a genetic disorder in which there is sticky, thick mucus buildup in many organs, which can eventually damage them. It causes a unique type of diabetes that has characteristic features of both type 1 and type 2 diabetes mellitus.

• Pancreatic Cancer - Pancreatic cancer and diabetes mellitus are interrelated. Long-standing diabetes is a risk factor for pancreatic cancer. 80 % of patients with pancreatic cancer have diabetes mellitus. Diabetes mellitus is a symptom of pancreatic cancer.

2. Hormonal syndromes that interfere with insulin secretion, like pheochromocytoma and PCOS (polycystic ovarian syndrome). Pheochromocytoma is a rare tumor of the adrenal glands. It affects metabolic activities like increasing glucose release and elevating blood sugar levels. PCOS is a condition that affects women's ovaries, causing an abnormal number of cysts to appear on the surface of the ovaries.

3. Hormonal syndromes that cause peripheral insulin resistance. For example-

• Cushing Syndrome - It is a disorder in which the body makes too much cortisol. Cortisol helps maintain blood pressure and regulate blood glucose.

• Acromegaly - It is an uncommon secondary cause of diabetes. Acromegaly is a condition in which there is an excess of growth hormone (GH). It, directly and indirectly, causes excess glucose in the blood and causes insulin resistance. This leads to diabetes mellitus.

4. Medications such as Phenytoin (used to treat epilepsy, trigeminal neuralgia, etc.), glucocorticoids (anti-inflammatory drugs), estrogen, etc. Among them, steroids are the most popular cause of drug-induced secondary diabetes. Most importantly, not only orally administered steroids but also cutaneous and inhalational steroids can cause an increase in blood glucose.

5. Syndromes such as Alstrom syndrome and Wolfram syndrome show features of diabetes mellitus.

What Are the Symptoms of Secondary Diabetes?

Although typical symptoms of high blood sugar are seen, symptoms of underlying cause for secondary diabetes are also seen. Some key symptoms of high blood sugar are,

• Increased thirst.

• Frequent urination.

• Extreme hunger.

• Unexplained weight loss.

• Presence of ketones in the urine.

• Fatigue.

• Irritability.

• Blurred vision.

• Delayed wound healing.

• Frequent infections of gum, skin, or vagina.

Apart from these symptoms, the symptoms of secondary diabetes can vary significantly depending on the condition which has caused it.

1. In cystic fibrosis, the symptoms are usually spotted within the first year of a baby's life. It includes-

• Salty-tasting skin.

• Persistent cough.

• Shortness of breath.

• Frequent chest and lung infections.

• Poor growth or weight gain.

2. In hemochromatosis, which is sometimes referred to as bronze diabetes, the symptoms are seen after the age of 40. The symptoms include-

• Darkening of the skin that is unexplained bronzing or tanning of the skin.

• Abdominal pain.

• Fatigue.

• Joint pain particularly affects the fingers.

• Erectile dysfunction.

• Missed periods.

• Loss of body hair.

• Weakening of the heart (cardiomyopathy).

3. In pancreatitis, nausea, vomiting, diarrhea, and fever are seen. The pancreas becomes very painful.

4. The symptoms of PCOS include irregular periods, fertility problems, weight gain, excessive body hair, thinning or loss of hair, acne, etc.

5. In Cushing syndrome, there is abdominal striae, hirsutism in females, and excessive fatty buildup in the waist, upper back, shoulders (truncal obesity), and face. There are also pink or purple stripes (stretch marks) commonly seen in the abdomen, near the armpits, breasts, and thighs. The skin is thin and bruises easily.

How to Diagnose Secondary Diabetes?

Diagnosis tests for the underlying cause are to be done primarily.

Cushing's syndrome can be diagnosed by measuring levels of cortisol in the urine, blood, and saliva.

If pancreatic diseases are suspected, the following investigations are suggested, along with urine and blood tests that include

• Chest X-ray.

• Ultrasound scan.

• Computed tomography scan.

• Magnetic resonance imaging of the pancreas.

An oral glucose tolerance test (OGTT) or continuous glucose monitoring is done to diagnose high blood sugar levels. Yearly screening is recommended for obese individuals and women with a family history of type 2 diabetes. Criteria for diagnosis of diabetes include the following test results:

• An HbA1c (glycated hemoglobin) level of 6.5 % or higher.

• A fasting glucose level of 126 mg/dL or higher.

• A 2-hour plasma glucose level of 200 mg/dL or higher during a 75 g oral glucose tolerance test. Random plasma glucose of 200 mg/dL or higher with classic symptoms of diabetes.

How to Manage Secondary Diabetes?

The cause of diabetes varies, and therefore how blood glucose levels are controlled can also vary. Treatment of the underlying cause is done. Lifestyle changes are an essential part of the treatment. It includes frequent meal intake, losing weight gradually, replacing carbohydrates with a whole grain diet, and increasing physical activity. If medications are required, Metformin is the most commonly prescribed drug.

In some forms where there is a loss of pancreatic function, injections of insulin will be required to keep the blood sugar levels under control. People who had removal of the pancreas due to cancer or some other reasons may not be able to make up insulin, and hence, they will have to take regular insulin injections. In patients with endocrine tumors (pheochromocytoma) or cancer in the pancreas, anti-tumor therapy such as chemotherapy or surgery will be required.

Conclusion:

The outcome of secondary diabetes depends on the underlying cause. Caring for patients with secondary diabetes includes eliminating the symptoms and preventing or at least delaying the complications. Secondary diabetes is permanent in most cases, but sometimes, they are reversible or controlled with medicines. In addition, people with diabetes can benefit from education about the disease and lifestyle changes. Finally, education about the disease and family support plays a key role.