Type II diabetes and depression are co morbid, which means they happen together more than expected based on the rates of each disease alone. The question among scientists is whether one disease can cause the other or whether there are factors that lead to both at the same time.
For example, having type II diabetes might cause people to feel more depressed because they are sick. Likewise, having depression might cause people to not eat healthy or get any exercise and lead to diabetes. The relationship might be as simple as that.
Is there more to the story?
Many scientists, me included, feel that there are common lifestyle factors that lead to type II diabetes and depression at the same time. There are an abundance of studies implicating exercise (or lack of it) in the onset of both diseases. There are also many studies highlighting the role of nutrition in both diabetes and depression.
Now, a new study, published in the October 2007 edition of PLOS Biology, sheds more light on this relationship with a focus on insulin at the center. Anyone with diabetes is well versed in the importance of insulin. It is a primary hormone that controls blood sugar levels, which the body needs to maintain tight control over for survival.
Insulin has many jobs
Your pancreas releases insulin into your bloodstream whenever blood sugar levels rise. It then goes around knocking on the doors of cells throughout your body telling them to take some sugar out of the blood and use it to make or store energy.
In type II diabetes two things go wrong. One, your pancreas becomes less responsive to making and releasing insulin; and two, cells throughout your body start to ignore the insulin that is released. Since insulin is important in so many different body functions, this becomes a serious problem.
The findings in the new study revolve around another role of insulin in the brain. The researchers discovered that dopamine activity in a part of the brain that promotes feelings of pleasure and reward are dependent upon insulin. In my opinion, this has a couple of far reaching implications.
Does insulin promote addiction?
The research suggests that diabetics, who lack the ability to produce insulin, will have a more difficult time feeling joy and pleasure because the brain circuits that control these feelings will be less active. This may be one link between the co-occurrences of type II diabetes and depression.
From a scientific perspective, this is a very interesting finding. But from a health perspective how does it help us prevent these diseases in the first place? This is where the next implication comes in.
The new research suggests that rises in insulin might boost the activity of pleasure and reward centers, the same ones that are stimulated by addictive drugs like amphetamine and cocaine.
When does your insulin go up? It goes up after a high sugar meal. What does this mean? It means that high sugar meals might stimulate addictive centers in the brain.
Ive been touting the benefits of feeding yourself and your kids low-glycemic (essentially low sugar) meals for some time. This new research adds fuel to that argument by suggesting that sugar might actually be addictive. Maybe not in the same sense that elicit drugs are addictive, but that they have some degree of addictive tendencies themselves.
The irony is that eating high-glycemic meals actually makes you feel good in the short-term by increasing insulin and boosting activity of your brains pleasure centers. But after years of eating sugar your pancreas will eventually burn out and lead to type II diabetes and possibly depression, leaving you with the opposite feelings that you ate the sugar for in the first place.
The take home message?
Get the high sugar cereals and other foods out of your house. Dont set yourself and your kids up for a lifetime of battling the cravings for these disease promoting foods.
