Does Stress Lead to Increased Diabetes Risk?

It is believed that improperly unmanaged stress is a major determinant in almost all illness conditions. Does stress also leads to diabetes? Let us investigate.

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

Type 1 diabetes mellitus is also known as juvenile diabetes because it starts in children and young adults. It is due to insufficient amount of insulin being produced (known as insulin deficiency). Since it does not start later in life, we can safely conclude that type 1 diabetes mellitus is unlikely to be caused by stress.

Type 2 diabetes mellitus usually occurs later in life, after the age of forty. Type 2 diabetes mellitus is the most common form of diabetes. In type 2 diabetes mellitus, the problems arise because

1. Either the body does not produce enough insulin, or
2. The insulin produced is ignored by the cells in the body (known as insulin resistance), or both.

Discussion on what insulin is and what the roles it plays is in order.

Insulin is a hormone that regulates carbohydrate metabolism (and to some extent fat metabolism as well). Insulin helps the body to use sugar. Sugar is the basic source of energy for the cells in the body, and insulin takes the sugar from the blood into the cells.

When we say blood sugar, we refer to glucose in the blood because glucose is the main type of simple sugar in our blood. Our body needs to have glucose level controlled to within a narrow range (0.7-1.1 mg per ml). Below 0.7 mg per ml is termed "hypoglycemia", and above 1.8 mg per ml is termed "hyperglycemia". Both can result in problems as we shall see later.

When there is more glucose in the blood, more insulin is secreted into the blood, resulting in cells (muscle cells, red blood cells and fat cells) absorbing the glucose out of the blood, thus reducing the blood glucose level.

When there is less glucose in the blood, more glucagon (counter part of insulin) is secreted into the blood, stimulating liver to release the glucose it has stored in its cells into the blood stream, thus increasing blood glucose. Glucagon also induces the liver and some of the muscle cells to produce glucose out of protein.

If the glucose does not go into cells, instead it builds up in the blood, two problems arise. Firstly, if the cells do not get the glucose they need, they die. Secondly, prolong period of high blood glucose levels may hurt your eyes, kidneys, nerves or heart. Insulin is used to treat this "hyperglycemia" aspect of diabetes.

"Hypoglycemia" or low blood glucose level condition can happen when more insulin is introduced than there is food in the stomach to be acted on. This often happens when a patient injects insulin in anticipation of food consumption, but the food consumption is delayed or insufficient food is consumed. Symptoms of "hypoglycemia" include strange behavior, clumsy or jerky movements, seizure, confusion, tingling sensations around the mouth, dizziness, sweating, headache etc.

Now that we understand the mechanics of diabetes, is there anything to suggest that stress can cause diabetes (type 2)?

The usual reason explaining where stress lead to sickness is the weakening of our immunity system caused by stress. However, diabetes is not caused by weak immunity system.

Psychological stress caused by the death of a spouse, a financial crisis or other life-altering event has been associated with higher risk of developing diabetes in middle age. Many studies have shown that the abovementioned types of major life events were associated with type 2 diabetes regardless of family history of the disease, exercise or alcohol use. However, although such circumstantial evidence seems to suggest a link between a higher proportion of people under greater stress and diabetes, we cannot conclude that stress cause diabetes.

There is a theory that says that stressful life events increase the diabetes risk by increasing levels of the hormone cortisol and decreasing levels of sex steroids such as testosterone, which have been shown to influence the action of insulin.

Some researchers have tried to determine whether stress, which can be measured using the ratio cortisol/testosterone, affects insulin resistance. In the prospective study by George Davey Smith and colleagues from the University of Bristol in the United Kingdom, cortisol/testoterone ratio was positively associated with IHD (ischemic heart disease) mortality and incidence. Adjustment for potential socioeconomic and behavioral confounding variables had little influence on these associations, but they appeared to be mediated by components of the insulin resistance syndrome (elevated blood pressure, triglyceride levels, body mass index, total cholesterol, HDL cholesterol, and impaired glucose tolerance). This suggests that methods of reducing the cortisol/testoterone ratio may improve insulin resistance and reduce the risk of ischemic heart disease (IHD). But, it does not suggest that reducing stress can reduce the risk of diabetes.

More conclusive research findings will be needed before we can conclude that stress does indeed lead to diabetes.

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