What makes Type 2 diabetes such a difficult disease to comprehend is that it is intricately linked to numerous other problems. If you look up almost any medical disorder in an encyclopedia, somewhere in the article you will probably find a statement to the effect that this problem is especially common in people with diabetes.

Whether it's gum disease, sleep apnea, or "frozen shoulder", diabetic people are likelier to have it than the general population is. (You know those customers who stand ahead of you in the grocery checkout line debating some trivial matter with the clerk, until you want to start throwing your canned goods at them? Whatever it is that's wrong with these people, you can bet someone has done a study proving it's more common in people with diabetes.)

Because diabetes doesn't like to travel alone, and always has a few other disorders along for the ride, it can be very difficult to analyze diabetes in terms of cause and effect. For example, there is known to be a lot of overlap between people with diabetes and people with hypertension, but what does that really tell us? That diabetes causes hypertension? That hypertension causes diabetes? That diabetes and hypertension are both caused by some third factor? 

You could, if you wanted, take the attitude that it doesn't matter why Type 2 diabetes and some other disorder tend to go together. That is, if you have both problems, you treat both, and you don't need to lose any sleep over what the connection is between them.

I am unwilling to take this indifferent view of the matter, partly because I have too much scientific curiosity, but also because I think it is important for anyone managing multiple health problems to understand how they affect one another, at least to the extent that this is possible. When it comes to diabetes, an ounce of prevention is worth many pounds of cure, and prevention usually requires us to know something about what causes what. So, if you ask me, it is well worth studying the connections between diabetes and other health problems.

It is especially worthwhile to understand that the ineraction between diabetes and other problems is usually not a one-way transaction. That is, you can't just think of these other disorders as a set of medical problems that are caused by diabetes. In many cases, these other problems also play a role in causing diabetes, or in making it worse. Clearly, you can't afford to remain uninformed about anything that has the potential to make your diabetes worse, especially if there's something you can do about it. 

Diabetes and inactivity

That Type 2 is strongly associated with obesity is well-known, and often discussed. That Type 2 is also associated with physical inactivity is less well-known, and seldom discussed. I think this is a mistake; inactivity is probably just as important an issue as obesity is, and maybe more so.

Sorting out the relative importance of inactivity and obesity in causing diabetes isn't easy, because the two problems usually go together. After all, becoming inactive tends to make people gain weight, and gaining weight tends to make people less active, so how do you untangle the two? Still, it won't do to pretend that they aren't separate issues, and talk only about weight.

There is every reason to suspect that inactivity plays an independent role in promoting insulin resistance. For one thing, exercise reduces insulin resistance almost immediately, and this is true whether you are fat or not. Going without exercise for a long period has the opposite effect.

When you exercise, the exertion stimulates your body to make a variety of adaptive changes to improve your fitness. The more obvious changes include expansion of blood vessels and muscle mass (you don't need an electron microscope to spot those particular changes). The less obvious changes take place in cell membranes, and these changes make it easier for the cells (especially muscle cells) to take in glucose from the blood. When you're at rest, your body obtains most of its energy from fat (an efficient but rather slow-burning fuel). However, when you're working out, your body is forced to use energy at a much faster rate, so it needs to start burning sugar (a less efficient but faster-burning fuel). Therefore, during exercise  changes take place in the cells which allow them to absorb and use sugar at a rapid rate.

For example, there are molecular structures known as "GLUT4 transporters" inside muscle cells which (when stimulated by insulin) flock to the cell membrane, grab glucose molecules from the blood, and pull them inside the cell. Exercise stimulates the cells to grow a lot more of these structures, and it apparently makes them more sensitive to insulin, so that they can pull in glucose as fast as possible.

The nice thing about these changes is that they don't come to an end the moment your workout is over. They do fade, but they fade slowly, over the course of a couple of days. Therefore, if you work out regularly, you get a continuing benefit between workouts. People who exercise regularly are more insulin-sensitive. This is true even if you don't have Type 2 diabetes; a study conducted in Switzerland in 2006 compared the "glycemic index" (a measure of how much a given food raises your blood sugar) in healthy young men of normal weight who had different levels of physical fitness. It turned out that the glycemic index (for the same breakfast cereal) was highest in those who didn't exercise, lower in those who exercised moderately, and lowest in those who were "endurance trained". And the difference wasn't small; the endurance trained subjects were 23 points lower than the sedentary subjects. To put that in perspective, there's only a 15-point difference between the "low" and "high" ranges of the index.

If exercise makes that much difference for people who don't even have diabetes, imagine how important it can be for someone who does.

Diabetes and obesity

Because insulin resistance typically develops after weight gain, and is typically alleviated by weight loss, it seems clear that obesity plays an important role triggering insulin resistance. Just how it does that is less clear. Apparently body fat can function like an endocrine gland, exchanging chemical signals with the liver and other organs; one of the consequences of that (if too much fat is present) is suppression of insulin sensitivity.

However, the relationship is not a one-way street. If weight gain promotes insulin resistance, insulin resistance also promotes weight gain! Specifically, insulin resistance derails the appetite control system. The release of insulin which occurs whenever you eat a meal is supposed to kill your appetite, but if you're insensitive to insulin that doesn't happen.

Insulin-resistant people tend to be hungry all the time, so it's only to be expected that they will gain weight. Even if you're not overweight when you first develop insulin resistance, the chronic hunger which insulin resistance can cause is likely to make you gain weight soon afterwards. The great majority of Type 2 patients are overweight by the time their diabetes is discovered, but they might not have been overweight when the underlying problem of insulin resistance first went to work on them.

Obviously the connection between obesity and insulin resistance is a vicious circle, with each problem making the other one worse. That doesn't mean the two problems are unsolveable, but it does mean that you have to attack both of them pretty aggressively if you want to break the cycle. You have to bring your weight down (by limiting your calorie intake) and bring your insulin sensitivity up (by exercising so much that casual onlookers think you enjoy it). Neither of these things is easy; both of them are necessary. Tough as it is to break a self-reinforcing cycle of this sort, you at least have the comfort of knowing that it gets easier as you go along. (It certainly has become easier for me.)

Diabetes and sleep disorders

There was a famous study of sleep deprivation which had to be abandoned prematurely because the test subjects (healthy young volunteers) exhibited an alarming physical change: they were becoming diabetic. Nobody knows why, but sleep deprivation promotes insulin resistance, even in people with no history of diabetes or other health problems.

Unsurprisingly, the risk of diabetes is much higher in people who suffer from disorders which interfere with sleep, such as insomnia, apnea, and even snoring.

This issue has great personal significance for me, because my own diabetes developed at a time when I was suffering greatly from a sleep disorder (obstructive sleep apnea, or OSA). OSA is sort of like snoring carried to a higher level: the soft palate settles down and blocks the airway entirely. When the condition is severe, this happens pretty much every time you fall deeply asleep. Naturally, the body goes into emergency response mode when your airway is blocked; it releases enough adrenaline to wake you up, or at least to move you up from deep sleep to shallow sleep, so that you start breathing again. But as soon as you settle into deeper sleep, the crisis repeats itself.

The result is that you are never deeply asleep at any point during the night. The shallow sleep you do get doesn't meet the body's needs, so in the daytime you are constantly sleepy. You fall asleep in meetings, in conversations when you're not the one speaking, at stoplights when you're waiting for the light to turn green. I don't really have the language to describe how awful this zombie-like state of existence can be. However, bad as it was, I was afraid to seek medical help for it, because my brother who had the same problem was given a painful throat operation for it which didn't work. Eventually I found out there was a nonsurgical remedy available (a breathing mask you can wear at night) which solves the problem. While I was getting treated for that problem, it was discovered that I had become diabetic.

Is this another two-way relationship? That is, can diabetes cause sleep disorders? Well, it might contribute to OSA, because a major cause of that problem is obesity, and Type 2 promotes weight gain. (I eventually was able to get rid of my OSA problem by losing weight). I don't know if diabetes can contribute to insomnia, although I get the impression that a lot of people who are having trouble managing their diabetes tend to lose sleep over it. I guess the bottom line is: be aware that getting an adequate amount of sleep is required for good glucose management, and if you're having any sleep problems (or simply feel mysteriously tired in the daytime), you need to look into it.

If you think you have a serious sleep disorder such as OSA, and you want to get your doctor to take it seriously, one good way is to say that you've been having trouble staying awake while driving lately. (That's a pretty serious issue, by the way; sleepy drivers are thought to cause at least as many crashes as drunk drivers.)


Diabetes and mood disorders

This one is really hard to untangle. Diabetes patients have a famously high rate of depression, but does that really require any explanation beyond the fact that it's depressing to have a chronic disease?

Diabetes has a lot of aspects which tend to make it a difficult disease to cope with:

Maybe it is only natural for people to get depressed when they're dealing with a set of problems like that. However, I think diabetes has other ways to make us depressed.

One of the great promoters of depression, at least in my experience, is inactivity. Exercise raises the spirits (primarily by releasing endorphins, a set of hormones which tickle the same receptors that are tickled by opiates). People with Type 2 diabetes are often sedentary (either by nature or because the disease is making them feel too bad to exercise), and sedentary people never get that endorphin boost. Going without it seemingly leads to depression.

It also leads to stress, which is an actively harmful state of being because it releases the stress hormones adrenaline and coritsol. These sterss hormones cause inflammation in the arteries, and the inflammation not only promotes insulin resistance (thus making your diabetes worse), it also promotes cardiovascular disease.

Another mood disorder (presuming that it's not just another form of depression) is "diabetic burnout", a dangerous but commonplace response to frustration with the difficulty of diabetes management. This is probably the most harmful emotional hazard associated with diabetes. Once people say to themselves, "Oh, to hell with it, I just don't care any more", things can take a dramatic turn for the worse. (If you thought fighting your diabetes wasn't getting results, wait till you see what happens when you're not fighting it.)

I have read a lot of research confirming the unsurprising news that people with diabetes are often depressed, but not any research that offers any fresh insight into what we can do about it. The only thing I know of that's very effective is exercise. Do a lot of it!

Diabetes and "frozen shoulder"   

In "frozen shoulder", also known as adhesive capsulitis, the shoulder capsule (which surrounds the joint) becomes inflamed, stiff, very painful, and immobilized by "adhesions" (bits of tissue which shouldn't be there).

It is almost hard to describe how painful and immobilizing the condition can be. I had a severe case of it last year, and I couldn't lift my left arm high enough to reach the steering wheel of my car. I could just barely dress myself (and it took minutes of painful maneuvering to accomplish this). I couldn't sleep in bed for a week, because there was no position lying down that didn't hurt; I had to sleep propped up in a reclining chair. A painful course of physical therapy eventually took care of the problem, but it was truly hellish there for a while.

Nobody knows what causes the condition (usually there is no history of trauma to the shoulder). What we do know is that it is very common in people with diabetes. Exactly how diabetes achieves this is hard to say, but presumably it has something to do with glycation (the bonding of sugar onto proteins, which causes tissue damage and may trigger an inflammatory response). At any rate, adhesive capsulitis certainly results in severe inflammation, and inflammation (see below) has a close connection with diabetes.

Because frozen shoulder typically starts out in a mild form (and should be treated with physical therapy before it become severe), let me at least tell you how to recognize it. Although the problem is actually in the shoulder joint, the pain is typically felt in the upper arm (it is "referred pain" from a nerve which passes through the shoulder to the arm). The pain is typically a kind of dull ache which doesn't seem to have a highly specific location within the arm. The ache tends to be worse at night, and may make it hard for you to find a comfortable sleeping position. If you hang your arm at your side and slowly raise it, swinging out to the side away from your body and continuing to swing upwards until your arm is straight overhead, you will usually find that your arm passes through an "arc of discomfort" -- that is, a segment of the half-circle through which it is impossible to move the arm without pain.

The thing is, most people (including me) who experience those symptoms just find a way to live with it. They learn not to move their arm through any angle that hurts, and they just find other ways to perform physical tasks to avoid such positions. The rest of the time, they're not hurting enough that they feel they need medical attention. However, when the problem finally gets really bad, it flares up literally overnight, and one morning you wake up to find yourself crippled and in severe pain. You don't want to get into that situation.

Unfortunately, if you want to do something about problem before it gets serious, you may be on your own. That is, you may have to find a physical therapist and pay the bills yourself, because your health insurer may not feel like helping you with a mild problem. All I can say is, if I knew how much agony I was going to experience in March of last year, I would have paid almost any price to have prevented it.

Also, adhesive capsulitis is an inflammatory disorder, and nobody with Type 2 diabetes should allow an inflammatory disorder to continue untreated if there's anything that can be done about it.


Diabetes and inflammation

Periodontitis (chronic inflammation of the gums) is very strongly associated with Type 2 diabetes; when dental treatment brings the inflammation of the gums under control, blood glucose levels usually come down. The reason for this oddity appears to be that inflamed tissues leak certain chemicals into the bloodstream, and these chemicals have the effect of triggering insulin resistance. In other words, inflammation seemingly has the power to make you diabetic, or to make your diabetes worse.

Clearly, anyone who has both Type 2 diabetes and gum disease needs to look into getting some good dental care, but the issue is larger than that. Inflammation, whether it's in the gums or anyplace else, has a tendency to elevate your glucose. If you have Type 2, any source of inflammation is cause for concern.

The thing is, inflammation can be a lot less obvious than raw, red gum tissue, or an infected wound.

A particularly worrisome issue is inflammation of the arteries, which leads to heart disease. In most people the inflammation is caused by stress hormones (adrenaline and cortisol) and/or high blood pressure. People with Type 2 have a third source of arterial inflammation to cope with: hyperinsulinemia.

If you have Type 2, your cells aren't as sensitive to insulin as they ought to be, so the endocrine system tries to compensate for that by pumping out unusually large amounts of insulin. (It's as if your body has become slightly "deaf" to insulin, so the insulin has to shout to be heard.) The trouble with this strategy is that insulin in abnormally high doses tends to trigger inflammation of the arterial walls.

So, once again we have a two-way interaction. Inflammation tends to make Type 2 worse, by reducing your insulin sensitivity. Type 2, in turn, tends to make inflammation worse, by flooding the arteries with extra insulin.

The way to break this cycle is to increase your insulin sensitivity, through exercise and weight loss, so that the body won't need to release such massive doses of the stuff into the bloodstream. Unfortunately, there won't be any way for you to monitor your progress on this issue directly; you probably aren't going to get a lab report which tells you how much insulin is in your bloodstream, and you probably won't get a lab report saying how much inflammation is going on in your arterial system (although that could change; there are measurable chemical indicators of inflammation, and they might become a routine target of lab tests). However, if you bring your glucose down to normal, that's a pretty good sign that your making progress on this front.

And, of course, you also want to deal with any other problem that is causing inflammation, anywhere in your body. (I never would have thought of dental floss as a form of diabetes therapy, but apparently it has a role to play there.)

Diabetes and cardiovascular disease    

I saw a presentation last month by a cardiologist who said that, when it comes to causes of heart disease, cholsterol deposits on the arterial walls represent only half the story, and not necessarily the more important half. And yet, that's where the medical profession concentrates nearly all its efforts. He said this might explain why, for all the new drugs and surgical procedures and implanted devices that cardiologists now have at their disposal, people are dying of heart attacks about as often as they were before.

The other half of the story, the neglected half, is the inflammation of the arteries which is caused by stress. Inflammed arteries are raw and easily wounded; they bleed and form clots (clots big enough to shut down a coronary artery and damage heart muscle). Doctors are fully aware of this issue, but they tend not to address it, because they think there's nothing they can do about it. (He thought differently, and was promoting a regimen of "breathe breaks" which can help people learn to reduce their stress level, and thus reduce the flow of stress hormones into the bloodstream.)

Anyway, if you don't want a heart attack, you don't want inflammation in your arteries. Unfortunately, as I've already described above, Type 2 diabetes tends to inflame the arteries by releasing abnormally large amounts of insulin ("compensatory hyperinsulinemia") in an attempt to overcome the body's insulin resistance. Not only does Type 2 tend to promote arterial inflammation, the inflammation tends to make Type 2 still worse by promoting insulin resistance.

Presumably that is why Type 2 is strongly linked with heart disease. Even if you you get your blood sugar under very good control, merely having Type 2 can more than double your risk of a heart attack. The arterial inflammation that comes with Type 2 tends to increase your cardiac risk, while simultaneously making your diabetes worse.

Anything you can do to improve your insulin sensitivity (mainly that means exercising a lot, and losing weight if you need to) is an important step toward reducing your risk of heart disease.