Monday, April 22, 2013

Stress, Sweets, & Syndromes


How stress can drive insulin resistance, metabolic syndrome, & diabetes

We know psychosocial stress can set one at risk for all sorts of disease. To add one more to the list - risk for developing type 2 diabetes has its correlations with the body’s stress response as well, specifically, a chronic stress response.

Individuals living with type-2 diabetes are often warned that stress can acerbate their conditions, putting their health at risk. In humans’ hunting and foraging days, our stress response helped us get out of trouble quick. And by trouble I mean, that hog we just tried to spear and missed is looking pretty angry, charging at our gut with six-inch tusks. Our stress response would be triggered, seconds later releasing more glucose into our bloodstream, to provide our bodies an energy boost to scramble up a tree to safety. We rarely suffer these same problems anymore, but our bodies wouldn’t know the difference.

Photo courtesy of Sidereal
{http://www.flickr.com/photos/sidereal/}
In a diabetic individual (type-2) with insulin resistance, glucose cannot adequately be taken up into storage and accumulates in the bloodstream. You may have already seen the connections; the glucose that gets unpacked and moved into the blood under stressful circumstance can unnecessarily add dangerous amounts to the diabetic’s blood supply. These elevated levels can lead to all sorts of another serious problems then.


But how can stress lead to diabetic, pre-diabetic or dysglycemic conditions?

There is a complex path on the way to
diabetes that stress can lead a primary role in, holding your hand the whole way. It starts with a sugar craving. If you’re anything like me, you – well, first, have quite the sweet tooth to start out with – but also, grab for anything sugary when feeling stressed out.

Many people cope with their stress by overeating or pursuing incentives. So, if your vice has always been sugar, you’re going to crave it when you’re stressed. Our brains release dopamine - that works on the pleasure-pathways (mentioned in my depression post) - at the beginning of a stressful event if there is a high probability of reward at the end of it (Sapolsky, 2004). Additionally, corticotropin-releasing factor (CRF) – experienced by us when we’re under stress – exaggerates cravings for a reward (Serwach, 2006). Humans have had a long and loving relationship with sugar; unsurprisingly, it is definitely reward enough for most of us.

Additionally, our bodies utilize increased levels of cortisol to mobilize glucose into the bloodstream when stressed. This is quickly followed by a rise in insulin levels, re-storing the glucose, to rebalance those circulating glucose levels. This quick rise and subsequent drop in blood sugar can leave us craving another quick form of relief from a quickly-metabolized sugar source.

As I’m sure you are exceedingly aware by now, psychosocial stress throws our bodies into a biological stress response a great many times in our modern era - most often without a physical means of energy expenditure to match. When work has us mentally running rampant and time is not on our side, we may find that a quick snack loaded with sugar holds us over just enough to make it through the day. Our brains employ a large amount of glucose to operate, but do not directly store it itself, so it must have a consistent supply from the blood. Heavy mental work can prompt a craving for sugar; that spike of energy may get the job done. However, continuing this pattern can lead to serious dysglycemic conditions, defined as a imbalance in sugar metabolism and energy production, characterized my abnormal blood glucose levels and associated with related diseases.

If this glucose yo-yoing keeps up a number of conditions can ensue. The first of which is hypoglycemia, literally referring to decreased amounts of glucose in the bloodstream. This is commonly associated with individual with diabetes but can be caused by a number of other reasons, including drug-related side effects and fasting. What we are concerned with here though is hypoglycemia in reaction to eating, specifically refined sugars. After a spike in glucose from a refined sugar, insulin takes effect, moving the glucose out of the bloodstream. In many cases, this results in an abnormally low level in blood sugar. If this effect is frequently occurring, we’ve got a hypoglycemic condition.

Hypoglycemia is often associated with insulin resistance in which beta-cells overproduce insulin and cause hypoglycemic conditions. Though insulin resistance syndrome is thought to involve a variety of genetic, lifestyle and dietary factors, psychosocial stress seems to play an important role in its emergence. Human clinical studies have linked chronic stress to enhanced sympathoadrenal reactivity, which increases fasting levels of glucose, insulin and lipids. Chronic stress has also been connected with a reduction in insulin-like growth factor-1 (IGF-1), the reduction of which is linked to glucose intolerance. Additionally, chronic stress has shown numerously to have a relationship with insulin resistance. The underlying mechanism between psychosocial stress and insulin resistance may include stress-related elevations in proinflammatory cytokines, which have been related to symptoms of depression, anxiety, cognitive impairment and traits such as anger, hostility and aggression which have been touched upon in previous posts. (Innes, Vincent & Taylor, 2007)

Insulin resistance syndrome is sometimes used synonymously with metabolic syndrome, previously known as syndrome x, but this condition actually describes multiple factors beyond just insulin resistance. Both, however, are used as indicators for risk of diabetes mellitus (type-2). Metabolic syndrome involves a group of risk factors for cardiovascular disease and stroke as well, including abdominal/visceral fat deposition, high triglyceride levels, low HDL cholesterol levels, high blood pressure and high blood sugar levels.

And guess what? The body’s stress response, characterized by the activation of the sympathetic nervous system and hormonal release of glucocorticoids, further stress these factors because they are causally linked. Psychosocial stress is significantly correlated with high blood pressure, atherosclerosis, increased levels of circulating cholesterol and triglycerides, increased blood sugar and fat deposition in the abdominal area. 




References:
Innes, K. E., Vincent, H.K., & Taylor, A. G. (2007). Chronic Stress and Insulin            
            Resistance-Related Indices of Cardiovascular Disease Risk, Part 1:
            Neurophysiological Responses and Pathological Sequelae. Alternative
            Therapeutic Health Medicine. 13(4) pp 46-52. Retrieved from
            http://www.alternative-therapies.com/at/web_pdfs/innes.pdf
Sapolsky, Robert M. (2004). Why Zebras Don’t Get Ulcers: The Acclaimed Guide to
            Stress, Stress-Related Diseases, and Coping. New York: St. Martin’s Griffin
            Press.
Serwach, Joe (2006). Bitter Truth: Stress Drives Sweet Craving. The University
            Record Online: The Regents of the University of Michigan. Retrieved
            From http://www.ur.umich.edu/0506/Apr17_06/04.shtml

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