April 10, 2008

Scare of the Day: Diabetes & Alzheimer's

Yesterday's bit of depressing news for people with diabetes is a Swedish study that is being reported in the news with headlines like "Alzheimers Risk Tied to Diabetes in Middle Age"

The abstract of the actual study is HERE
It is titled, "Impaired insulin secretion increases the risk of Alzheimer disease."

Apparently they gave a group of 2,322 men intravenous glucose tolerance tests in 1970 and then followed them for the rest of their lives tracking which ones developed Alzheimer's disease and dementias.

The researchers conclude, "A low insulin response at baseline was associated with a higher cumulative risk of AD. Impaired glucose tolerance was associated with a higher risk of vascular dementia."

Unfortunately, from the brief description available in the free abstract, it isn't clear what they actually measured. They did intravenous glucose tolerance tests, but the way the report mixes the terms "insulin response" and "insulin resistance" does not make it clear whether they are talking about low insulin secretion or high insulin resistance, and these are two very different metabolic issues.

[NOTE: Dr. John Griffa informed me that the study DID measure insulin levels.]

Beyond that, though, before we conclude that it is only time until our brains are toast, we have the problem, once again, that the study is not able to tell us whether the brain damage was caused by the underlying condition that causes insulin resistance and/or insulin deficiency of if it was the result of long term exposure to the high blood sugars that doctors fail to treat aggressively in people who have either insulin resistance or insulin deficiency.

If it's something in the genes causing the damage, well, a lot of us are screwed. But if, like so many other diabetic complications, the damage is done by exposure to high levels of circulating glucose which gradually clog up the works all over the body, we aren't.

And in a world where doctors tell patients that A1cs of 7.2% are "great control" and refuse to give any treatment to most people with Type 2 diabetes until their A1cs are well over 8%, most people with IR and insulin deficiency under a doctor's care are walking around with very high blood sugars indeed. So we aren't likely to see any studies that look at the incidence of either Alzheimer's or dementia in people who keep their blood sugars in the normal range, no matter what their IR or insulin secretory capacity.

If this latest report worried you, remind yourself of this: No matter how bad your blood sugar might be, it is possible to get it back to normal levels. The tools are simple and well known.

1. Cut way back on carbohydrates. It is carbohydrates that raise blood sugar and the less carb you eat the less of a rise you will see in your blood sugar.

2. Exercise if you can. Exercise reduces insulin resistance and encourages glucose uptake in muscle cells.

3. If diet and exercise don't do the job, investigate which of the available, safe diabetes drugs might work for you.

4. If oral drugs don't work, use insulin and insist that your doctor work with you to find a dose that gives you good control.

Far too many doctors do not know that people with diabetes can get normal blood sugars. Hence their belief that the 7% A1c that represents an average blood sugar near 170 mg/dl is "good control." Even more doctors dismiss the blood sugar levels defined as impaired glucose tolerance as merely, "Nothing to worry about." This study makes it clear that they are more than that. Unless you think being demented is nothing to worry about.

A lot of recent research makes it pretty clear that blood sugars are over 140 mg/dl 2 hours after a meal very slowly damage capillaries, nerves and retinas. Now this new study suggests they are also clogging up the tiny veins in the brain.

But until there is some definitive proof that it is the underlying condition leading to insulin resistance or deficiency rather than exposure to high blood sugars caused by IR and ID, that does the damage, there is hope.

And there is also one more reason to strive for normal blood sugars, not the much-too-high blood sugars that the ADA defines as "tight control."


Anonymous said...

It would certainly not surprise me to see a connection between high blood glucose and Alzheimer's. Since we know for a fact that it impacts the smaller blood vessals in the limbs and eyes, and affects the kidneys and heart (and who knows what else?) why shouldn't it impact the brain in the same way?

My theory would be that Alzheimer's has a genetic predisposition, much like the tendency to develop certain cancers. I can say for sure in my family, the cancer element was widespread, in that a number of my mother's family developed fairly nasty cancers of the mouth , throat, and/or lungs. Of course they smoked, but each died from these cancers in their 40's. I can see that they were probably born with a "cancer gene" that made them suscepible to cancer, and that exposure to stress allowed that "cancer gene" to kick in.

In much the same way, I can see a predesposition to Alzheimer's, which when stressed by the vascular damage invariably caused by the glucose, could develop the desease either faster, or more agressively absent the stress.

My mother-in law is a case in point. She has had rather uncntrolled diabetes since her middle age, and is now suffering from kidney failure (on dialysis), and rather bad neuropathy. She is also exhibiting mild dementia. I cannot help but think there is a connection. I do see a genetic link, though, in that her mother died with severe dementia.

Her problems with her blood sugar are less the doctor's fault, though, than stubborness on her part to eat whatever she wants (candy, cakes, junk food, high carbs etc.), and a lack of care in monitoring her BS properly (she has wild swings daily). She does take insulin, but seems not to understand that she needs to do more than that.

Interesting post...

Russ said...

the study is not able to tell us whether the brain damage was caused by the underlying condition that causes insulin resistance and/or insulin deficiency of if it was the result of long term exposure to the high blood sugars that doctors fail to treat aggressively in people who have either insulin resistance or insulin deficiency.

Or, indeed, long term exposure to the wild barrage of medications given to diabetics by doctors, including, of course, those given in a frantic attempt to lower total cholesterol, an activity which has been tied to... dementia.

Does make one wonder.

Jenny said...

That's a good point about the statins as they have been linked to causing dementia in older people.

The thing about true Alzheimer's is that it has those cycloidal plaques and there are amyloid deposits in the pancreases of some people with Type 2, also, though it isn't known if this is the result of dying beta cells or the cause of dying beta cells.

So it is possible there is a connection, but whether it is causal, related to blood sugar or what is not known.

Lili said...

Wasn't there another study somewhat recently linking Alzheimer's to untreated or poorly treated insulin resistance? I remember thinking that the people at risk probably had Type 2 but went undiagnosed for years.

Anonymous said...

Dr. Briffa in the UK has been blogging about the connection with dementia.


Anonymous said...


Do you ever look at Dr. McLeary's blog on the brain?