Whenever the word diabetes (Mellitus or Insipidus) is mentioned and simultaneously heard, a certain kind of feverish and ironically cold shiver rushes down one's spine. It is because of nothing else but the infamy of the disease. Diabetes (Mellitus in particular) has sustained a convenient spot in the group of highly mortal anomalies over the years.
It is one of the most significant global emergencies, and as of 2015, statistics showed that it occurs in one in eleven adults and has since increased, especially in the urban areas. It has also led to more medical and economic challenges.
One of the most dreadful things about diabetes is that when it comes, it doesn't come alone but comes in handy with a cascade of other diseases which are also lethal. They are;
- abnormal structural changes in blood vessels, which can lead to heart attack, stroke, etc.
- peripheral neuropathy (disease of the peripheral nervous system), autonomic nervous system dysfunction, which can lead to impaired cardiovascular reflexes, impaired bladder function, etc
- depression (which is the focus of the article).
Depression is also a notorious disorder because it has a wide range of damaging effects on human health. And like diabetes, it is not only notorious. It also has a prestigious platform on the list of diseases that are a bane to the human populace in the area of health, with a lifetime prevalence ranging from 11% in low-income countries to 15% in high-income countries, thereby causing serious concern for the global health community.
Before we see how these two health disorders are associated, let's have a quick look at their distinct characteristics.
Depression and Diabetes: What are they?
Depression is up first for analysis.
We can say it is a psychological disorder that fosters the reduction of the efficient actions of the general state of mind. And it does affect millions of people worldwide. Different types of depression can be categorized by symptoms which are;
- Depressed mood
- Changes in sleep, appetite, and weight
- Less activity or more agitation
- Trouble concentrating
- Low energy
- Feeling hopeless or guilty etc
The use of the Diagnostic and Statistical Manual (DSM-5) by physicians in diagnosis is a determinant factor in whether the conditions of the supposed depressed person are fit to be characterized as depression or not.
Now, the types of depression include Major Depressive Disorder (MDD), persistent depressive disorder, bipolar disorder, seasonal affective disorder (SAD), perinatal disorder, premenstrual dysphoric disorder (PMDD), major depression with psychotic features, atypical depression, reactive depression, etc.
- Medications (SSRIs like Zoloft, Prozac, Paxil, Lexapro, etc.),
- Light therapy
- Brain stimulation therapies
- Cognitive-behavioral therapy
- Interpersonal therapy etc.
To do justice to the overview, let's have a summary of diabetes (Mellitus).
Diabetes mellitus is a syndrome of impaired carbohydrate, fat, and protein metabolism caused by either lack of insulin secretion or decreased sensitivity of tissues to insulin. There are two general classes or types of diabetes mellitus:
Type 1 Diabetes
Type 1 diabetes, also called insulin-dependent diabetes mellitus, is caused by a lack of insulin secretion. Injury of the beta cells of the pancreas (the islets of Langerhans) or diseases that impair insulin production can lead to type 1 diabetes (DM 1). Viral infections, autoimmune disorders, and heredity may also play a role in determining the susceptibility of the beta cells to destruction.
Research shows that the usual onset of diabetes mellitus in the United States of America occurs at about 14 years of age. For this reason, it is often referred to as juvenile diabetes mellitus. Nonetheless, type 1 diabetes mellitus can occur at any age, including adulthood, due to events that lead to the destruction of the pancreatic beta cells.
Type 1 diabetes mellitus may develop abruptly, over a few days or weeks and has three subsequent events which are worthy of note:
- Increased blood glucose levels:
Lack of insulin, which is essential for glucose uptake by cells, leads to increased plasma glucose concentration to 300-1200mg/100ml. The standard value is about 180mg/100ml of blood. This level is exceptionally high and leads to a series of other effects like glucosuria (appearance of glucose in the urine), osmotic diuresis, polyuria (frequent urination), tissue injury, etc.
- Increased utilization of fat for energy and the formation of cholesterol:
Suppose the rate of fat metabolism becomes too high. In that case, it results in the release of ketone bodies into plasma more than can be taken up and used by cells and results in metabolic acidosis (diabetic ketoacidosis).
- Depletion of body's protein:
The inability of the body to use glucose will lead to increased utilization and decreased storage of proteins which can cause rapid weight loss and lack of energy (asthenia). Treatment of type 1 is essentially centered on insulin administration.
Type 2 Diabetes Mellitus:
Type 2 is far more common than type 1 and is responsible for 90-95% of total cases of diabetes mellitus. In most cases, the onset occurs after 30years of age (often between 50-60 years of age), and in contrast to type 1, it develops gradually. Therefore, this syndrome is often referred to as adult-onset diabetes. In recent years, however, the rate of its occurrence in younger individuals younger than twenty years old has increased.
A fascinating and notable difference between type 1 and 2 diabetes mellitus is that instead of the hypoinsulinemia (low plasma concentration of insulin) in type 1, type 2 is characterized by hyperinsulinemia (high plasma concentration of insulin). This difference makes significant disparity with the different accompanying disorders that are evident in the two.
We may also say that there is a sequence of effects preceding type two instead of following it. They may include: obesity, insulin resistance (from here comes insulin-resistant diabetes), fasting hyperglycemia, lipid abnormalities, hypertension, etc. They are altogether called metabolic syndrome, and they lead to type 2 diabetes. Treatment may be around the regions of diet, exercise, and sometimes medications.
(Note: insulin is secreted in the beta cells of the islets of Langerhans, the endocrine part of the pancreas, the alpha cells secrete glucagon, a hormone that has the opposite effect of insulin).
Co-Morbidity Of Depression and Diabetes
Having gotten a basic understanding of these two ailments, we'll now move on to see how they can be associated. In the year 2015, two reviews showed three possible pathways for the association of these two diseases:
- Both of the diseases may have a common etiology (cause or origin)
- Diabetes increases the prevalence of risk for future depression
- Depression increases the majority of the risk for future diabetes.
There is no confirmation that there are genetic correlations between depression and diabetes. However, different environmental factors may foster the activation of a common pathway that can lead to type 2 diabetes and depression in the end. A low socioeconomic status increases the odds for DM2 and also seems to be a cause for depression. Other common causes are poor sleep, lack of physical exercise, etc.
The activation of the common pathway may be due to the disturbance of the stress system, which leads to high production of cortisol in the adrenal cortex also adrenaline and noradrenaline in the adrenal medulla. Chronic hypercortisolemia and prolonged sympathetic nervous system activation enhance insulin resistance, visceral obesity, metabolic syndrome, and ultimately type 2 diabetes mellitus.
On the depression side, chronic stress has behavioral consequences. Cortisol, noradrenaline, and other hormones activate the fear system determining anxiety. Anorexia (loss of appetite) produces depression. New studies show that the inflammatory response effect of cortisol is involved in the pathophysiology of depression. There are not many studies on the relations of DM1to depression, but they may have biological correlations.
Diabetic Risk in Depressed Patients
Several studies have confirmed that patients with depression have an increased risk of developing type 2 diabetes. A survey on antidepressant usage and hypoglycemic control showed that in adults with diabetes, the use of antidepressants minimized glycemic control. The short-term treatment of non-diabetic patients with these antidepressants has a beneficial effect except for noradrenergic antidepressants. SSRIs may improve glycemic control in type 2 diabetes patients on both short and long-term usage.
Continuous usage of antidepressants is significantly associated with the risk of developing type 2 diabetes. It is essential to understand the adverse effects of these drugs and try to minimize them.
Depression Risk in Diabetic Patients
It is crucial that we keep referencing studies (research works) in discourse such as this. So once again, studies in recent years showed that depression was more prevalent in people with diabetes. The same study showed that anxiety was more prevalent only in those who were aware of their diabetes. Probably because of the psychological burden of being conscious triggers anxiety and depression.
However, in patients with previously undiagnosed diabetes, depression was prevalent, possibly because of unfavorable lifestyles such as inactivity, unhealthy diet, or stressful lifestyle. Based on the hypothesis, depression can increase with antidiabetic treatment. A strong association between depression in patients in their forties with orally treated diabetes was found.
It is essential to prevent, identify, and treat health problems to have a healthy society with a high life expectancy. In diabetic patients, depression is underdiagnosed, and an essential aspect for the diabetes physician would be the awareness of this relatively common co-morbidity. A multi-disciplinary approach of the diabetic patient would help improve the outcome of diseases, decrease the number of DALYs (Disability Adjusted Life Years) and even mortality.