Diabetes For Beginners – Part 2

Welcome to Part 2 of my “freshman lecture” on Diabetes.

Now we get to Type 2 Diabetes Mellitus. Interestingly enough, although this is “Type 2”, it is in fact by far the Number 1 form of Diabetes numerically, with 90 to 95% of Diabetics falling into Type 2…and that number is likely, if anything, to become larger.

Individuals with Type 2 Diabetes do produce insulin, despite what you might think. In fact, oddly enough, many of them produce way MORE insulin than is good for their bodies. So what’s the problem, how can they be Diabetic? Well, the problem in Type 2 Diabetes involves insulin resistance by the cells of the body…especially the fat cells.

This insulin resistance usually starts off as just a sort of predisposition, where some people’s cells respond to insulin a bit more sluggishly than others. At first this doesn’t produce any obvious clinical results, because the pancreas responds to that sluggishness by just putting out more insulin when the glucose doesn’t get taken up fast enough. Unfortunately, this only works for a little while. That’s because the insulin resistance tends to increase as the cells respond to the higher amounts of insulin. In a way, they get used to it, rather like someone losing their hearing when being surrounded by loud noise all the time. Eventually, despite the fact that the islet cells are putting out way more insulin than they would in a healthy state, the body just stops responding well to it at all, and the blood sugar goes above normal levels. This is the clinical onset of Diabetes Type 2, but I think you can see that the real disease starts a long time before this happens.

Type 2 Diabetes is only very rarely associated with the horror of ketoacidosis, but that doesn’t mean it doesn’t have horrors all its own, and though they are subtle, they affect far, FAR more lives than any aspect of Type 1 Diabetes. Long before the blood glucose starts to goes up, individuals heading toward Type 2 Diabetes have chronically elevated blood insulin levels, and this has effects on more than just the blood sugar. It leads to elevation of serum triglycerides, for one thing, and as you may know, this is one of the “bad” forms of lipids (often collectively referred to as “cholesterol” though that’s not strictly accurate). The triglycerides in particular—and elevated insulin itself—increase the risk of coronary artery disease and other vascular diseases, and it’s probable that the chronically high insulin contributes to an increased risk of hypertension (also known as high blood pressure). The heart, the kidneys, the blood vessels, the eyes…eventually all the systems of the body are damaged by these processes.

Once the blood sugar is elevated, the overall effects of Type 1 and Type 2 Diabetes overlap a great deal, except as discussed above. Unfortunately, having extra blood sugar, as you might guess, doesn’t give a person extra energy. Quite the contrary, it usually leads to low energy, partly through dehydration as the sugar spilled in the urine takes water away with it, and partly from a simple inability of the body to use the glucose appropriately. People with untreated Diabetes tend to lose weight, but it’s not a good kind of weight loss. They lose lean body mass for one thing, and lean body mass is the tissue that responds best to insulin and helps lower the blood sugar and improve the overall health.

People with Diabetes also, unfortunately, develop a lot of complications from having just too much sugar throughout their system. You see, sugar is not a completely benign substance. Your mother probably made this clear to you long ago, but you may not realize just why it’s so. Glucose is a very chemically active substance, which is why it’s useful as a source of energy. But when it’s around in large quantities for a long period of time, it tends to react chemically with things with which we don’t really want it to react. For one thing, it binds very nicely—without any help—to various kinds of proteins, and then doesn’t tend to unbind itself. This can actually be useful in measuring how the long-term blood sugar has been, and is the subject of a test called the hemoglobin A1C, which measures how much of a certain type of glucose-bound-hemoglobin there is in the blood, giving a good estimate of how the blood sugar has been over about the last 4 months (Why four months? Red blood cells live about four months in the body, and they are where all the hemoglobin is).

Still, glucose binds to lots of other proteins in much less useful ways than this, and over time this binding tends to create dysfunction in the proteins, and in the structures of which they are part. Such binding happens in the proteins that make up small blood vessels—such as those that feed nerve endings, for instance—narrowing those vessels down until the nerve endings or any other tissues the vessels supply start to die. This (plus a bit of contribution from thickening of the vessel walls due to elevated insulin in the Type 2 Diabetes patient) is the cause of “Diabetic Neuropathy,” a numbness that develops, usually starting in the extremities and working its way up. Though the inability to feel pain might sound nice at first, it leads people to be unaware when they have, for instance, developed blisters and cuts on their feet. Cuts and blisters that are unknown tend to be untreated and thus prone to infection. To top that off, the elevated blood glucose itself makes a person with Diabetes an especial treat for many kinds of bacteria, and it interferes directly with the function of the immune system. This combination of factors leads many uncontrolled Diabetics to face the frightening prospect of infections that cannot be adequately treated and that lead to amputations.

Elevated blood sugar also affects the eyes in a number of ways: The effects of elevated insulin and sugar narrow the arteries in the retina (the sensing surface on the back of the eye) and lead to various consequent visual problems. In addition, the sugar causes fogging of the lens of the eye as it binds with proteins there, producing cataracts.

The kidneys, dealing with the high load of fluid and with the glucose that gums up its complex structure by binding to the proteins—complicated by the often-coexisting problem of high blood pressure—tend to deteriorate under the influence of Diabetes, and many Diabetics progress to kidney failure, requiring dialysis to stay alive.

There are, of course, many treatments available for the complications of Diabetes, though none are quite perfect. There are also treatments for Diabetes itself. Type 2 Diabetics can receive extra insulin to help overcome their insulin resistance, but this extra insulin can cause problems of its own and tends to lead to weight gain…and that gain is often in the fatty tissues, which leads to increased insulin resistance, and so the spiral continues.

There are medications—called sulfonylureas, not that the name is that important here—which stimulate the pancreas to release more insulin in response to blood glucose. But as with giving extra insulin from outside, this tends over time to increase resistance and can thus only go so far.

There are a number of other medications that can help with Type 2 Diabetes. Some suppress the liver’s uncontrolled creation of new blood sugar when it’s not responding to normal suppression by insulin. Some try to increase the body’s cells’ sensitivity to insulin. These medications all have their place and they all work to one degree or another. Yet none of them work as well as avoiding Diabetes in the first place, when possible.

Yes, in many people Diabetes can be avoided and/or largely corrected by some simple changes in lifestyle—well, they’re simple in concept, though carrying them out requires willpower and determination. The main interventions are: diet and exercise. Simply put, keep the intake of simple carbohydrates (that’s sugars and white starches, basically) to a minimal amount, and do regular exercise, especially aerobic exercise (exercise where you keep moving without break, such as walking, swimming, running, biking and so on) three or more times a week for a good half hour or more at a time. Of course, if you have underlying health problems, you need to check with your doctor before starting an exercise routine, and you certainly shouldn’t try to achieve Olympic level results right from the start. But the problems of Diabetes in individuals who are predisposed CAN often be minimized and even sometimes reversed by appropriate lifestyle choices, for as long as those choices are continued. It’s not literally a cure, but it can sometimes be the next best thing.

Well, this has been a very quick rundown of Diabetes, aimed at those who don’t know much more than the term itself and that it’s related to high blood sugar (and is NOT a good thing). I hope it’s answered some questions and…just maybe…stimulated some new questions in the reader. If you have any such questions, please, by all means, leave a comment with your question, whether it’s about something you’d like to know more about or just about something I wasn’t clear enough on in my explanation. I’d be delighted to respond.

Trying to help more people understand more about medicine and science is, after all, the whole reason I’m doing this.

Diabetes For Beginners – Part 1

Diabetes is an illness of which I suspect almost all adults in America are aware. I also suspect that most people know that it has something to do with high blood sugar and that having high blood sugar is a bad thing. Still, I imagine there are a fair few people out there who haven’t really got a lot more understanding of it than that—including some people who have the disease—because they haven’t really had it explained to them in terms they can follow. After all, doctors—of which I am one—don’t often take the time necessary to make sure that their patients fully understand the ins and outs of a disease process. Partly this is because, when one understands something on a very complex level, it seems like it’s going to take serious effort to explain it to someone who doesn’t have the same educational background. However, I think this is a failure of imagination and a bit of mental laziness on our part as doctors. The Nobel-Prize-winning physicist Richard Feynman used to prepare “freshman lectures” about physics subjects when laypeople asked him about topics they didn’t understand. If he found that he couldn’t prepare one, he recognized that failure as an indication that the subject wasn’t well-enough understood!

I just love that philosophy and attitude. So, since Diabetes in general is pretty well understood, I’m going to try to give a “freshman lecture” here on Diabetes.

First off, “Diabetes” is actually only part of the name of the disease we’re going to be discussing. The full name of the disorder is “Diabetes Mellitus” and this diagnosis is then subdivided into Type 1 and Type 2. The term “Mellitus” serves to differentiate the common disease known as Diabetes from the far-more-obscure disorder “Diabetes Insipidus,” which I will not really be discussing here.

You see, the word “Diabetes” is a Late Greek word meaning “excessive discharge of urine.” That’s originally all the word referred to, since that is the most noteworthy presenting problem in both kinds of Diabetes. The meaning of the second words in the disease names is going to gross a few people out, and that’s completely understandable. You see, “Mellitus” means (more or less) sweet-tasting, whereas Insipidus—and this will be obvious when you think about it—means “tasteless”.

Sweet? Tasteless? What is sweet or tasteless?

The answer is: That excessive discharge of urine. Yes, in the old days, one way they used to diagnose things was to taste the urine, and the urine in Diabetes Mellitus tasted sweet. Why? It tasted sweet because it was just full of glucose.

Well, urine is not SUPPOSED to be full of glucose! Nature has designed our bodies to want to hold on to glucose, either so we can use it directly as fuel or convert it into one or another storage form that we can use for energy later. Nature doesn’t deal very kindly with creatures that waste precious energy…when survival is at stake that’s a really bad strategy. So the kidneys ordinarily filter the glucose out of urine before it’s passed to the bladder for elimination. Only when the glucose is quite a bit above normal range is the kidney’s ability to do this overwhelmed, and sugar (glucose) starts to spill into the urine and be wasted.

So, how does the blood sugar get so high? Well, ordinarily, the level of sugar in the blood is pretty tightly controlled, mostly by the actions of two major hormones: glucagon and insulin. Most people who have heard of Diabetes have probably heard of insulin. Insulin is a type of hormone called a peptide, which means it’s a small, clipped version of a protein. It’s produced in the pancreas by a group of specialized cells called beta islet cells in an area called the Islets of Langerhans. The name isn’t really that important, except that things have to be given names so we know what we’re talking about when we’re talking to each other. The cells in the pancreas that make insulin were first described by a scientist named Paul Langerhans, so they got named after him. That’s how it works with a lot of obscure medical terms.

Insulin is secreted (released, in other words) by the islet cells in response to the sensed level of glucose in the blood. The more glucose there is, generally, the more insulin is released. Why is this necessary? Because the cells of the body only take up glucose when they’re stimulated to do so by the action of the hormone insulin. Insulin is, quite literally, the signal that tells cells to activate the machinery they use to take glucose in, after which they can digest it for energy to run their metabolism, or they can store it for burning later. So, when we eat and our digestive systems bring glucose into our blood, the glucose level rises, the islet cells release more insulin and the cells take up more glucose. It’s a good system, and usually it works brilliantly.

Incidentally, glucagon, which I mentioned before, is in a way the opposite of insulin. It is released in response to lower blood sugar, and stimulates the release of glucose from storage or the creation of new glucose by the liver. These two hormones—insulin and glucagon—in a healthy person, work beautifully in counterpoint, and maintain the blood sugar between roughly 60 and 100 milligrams per deciliter at all times. It’s a lot like the cruise control on a car, which applies a little more or less power as needed to keep the speed where you set it. A healthy body has a very tight and responsive glucose cruise control.

Diabetes happens when the insulin system breaks down. There are two main ways that this happens, and there are, therefore two main kinds of Diabetes…very cleverly called Type 1 Diabetes and Type 2 Diabetes.

In Type 1 Diabetes, there is a failure of the beta cells in the Islets of Langerhans…usually caused by some kind of inflammation destroying those cells. When this happens, there is no longer any production of insulin to speak of, and without insulin, the cells of the body don’t take up blood sugar. Without blood sugar, many of the cells of the body cannot get new energy, except by very specialized and limited means that have their own downside to the body when they operate without restraint. A person with Type 1 Diabetes absolutely requires the administration of insulin from an external source. This is usually done by injection into the subcutaneous tissue by a fine needle, generally a number of times a day. Without this treatment, a person with Type 1 Diabetes will not be able to get glucose into their cells. They will lose oodles of glucose in their urine, they will rapidly lose weight and dehydrate (because all that spilled glucose in the urine carries a LOT of water with it), and ultimately they will go into a catastrophic state called “Diabetic ketoacidosis.” I won’t get into the specifics of this right now, but it DOES involve the blood becoming quite a bit too acidic, among other things. None of the effects involved are good for the function of a human body, and unless treated quickly and given replacement insulin, a person in Diabetic ketoacidosis will die.

Wow, that’s pretty scary, isn’t it? Fortunately, nowadays we have a number of different forms of readily available and inexpensive injectable insulin for Type 1 diabetics to use…and there are scientists working all the time on better ways of treating this disorder, including working on developing insulin that can be given without injection and transplantable replacement islet cells. Stem cell research may be able to deliver that last modality in readily workable form, without the worry about tissue rejection, so we should all do everything we can to support such research.

Well, this has already gotten pretty long, so that’s going to be it for the first half of the article. I’m going to continue this discussion, of course, in Part 2 which will, appropriately, start with the subject of Type 2 Diabetes Mellitus.