In the vast majority of cases diabetes can be grouped into two major classes: the kind caused by loss of the ability to produce insulin and the kind caused by insulin resistance (the body’s inability to utilize insulin properly). Now here’s where it gets interesting: people who lose the ability to produce insulin can sometimes develop insulin resistance, and those who have insulin resistance sometimes lose the ability to produce insulin.
Confused yet? Don’t worry. You’re not alone. Let’s see if we can sort it all out.
All forms of diabetes involve blood sugar levels that are too high.
This is called hyperglycemia .
Hypoglycemia (low blood sugar) can also occur when insulin or insulin-enhancing medications (sulfonylureas or meglitinides) are used in treatment.
All require careful ongoing management, and all can produce a wide range of health problems (complications).
However, the similarities stop there.
From a physiological standpoint, the various forms of diabetes and their modes of treatment vary like flavors of ice cream.
First, let’s look at the vanilla, er, type 1 diabetes.
Type 1 Diabetes (Vanilla)
Type 1 diabetes involves damage to the pancreas, a slimy organ nestled below the liver.
At the base of the pancreas is a cluster of cells called the islets of Langerhans, named after the person who discovered them who, interestingly, had no clue about what they did.
Contained within the islets are alpha cells (which make the hormone glucagon), gamma cells (which make the hormone somatostatin), and beta cells.
The beta cells constantly measure blood glucose levels and produce insulin, as needed, to keep blood sugar within a normal range.
Beta cells also secrete amylin, a hormone that helps regulate the rate at which food digests.
In type 1 diabetes the body’s own immune system destroys the beta cells.
Normally, the immune system only attacks things that are not part of your own body, like viruses and bacteria.
With an autoimmune disease such as diabetes, the immune system fails to recognize a part of your own body and attacks it, thinking that it doesn’t belong.
In the case of type 1 diabetes, the beta cells are attacked and gradually destroyed over a period of months or years.
When enough beta cells have been destroyed and insulin production reaches a critically low level, the blood sugar level goes up, and the body’s cells are deprived of the sugar they need for energy.
In type 1 diabetes, the body’s own immune system destroys the insulin-producing beta cells within the pancreas.
There are nearly 1.5 million people with type 1 diabetes in the United States, and several times that number worldwide.
Tens of thousands are diagnosed with type 1 diabetes every year.
Type 1 diabetes may be diagnosed during childhood and adolescence, but half of all diagnoses are made in young and middle-age adults (this is why we no longer use the term “juvenile diabetes”).
Most people with type 1 diabetes were born with a faulty immune system, prone to attacking things it shouldn’t.
We now have the ability to test for autoimmune markers, antibodies that increase the risk of a person developing diabetes at some point in their lifetime.
However, even in people who have multiple markers, it is impossible to say with certainty when or if diabetes will develop.
We simply don’t understand enough about what triggers the immune system to begin attacking the beta cells of the pancreas.
Viruses, major stress, environmental toxins, exposure to certain foods at a young age, and genetic tendencies have been proposed as potential triggers.
At the time of diagnosis, a person with type 1 diabetes will likely have a very high blood sugar level and elevated ketones .
Ketones are acids that form from the breakdown of large amounts of fat by cells that are starving for glucose.
Blood sugar levels above 180 mg/dl (10 mmol/l) tend to cause excessive urination, as the kidneys pass some of the sugar from the blood into the urine.
In essence, high blood sugar causes you to urinate away many of the calories you consume.
Consequently, you can lose weight rapidly.
Frequent urination also makes you very thirsty.
And because you are unable to get sugar into your cells without insulin, your energy level will be quite low, and you will be constantly hungry.
Nowadays, physical symptoms are not enough to make a true diagnosis of type 1 diabetes.
It is usually also necessary to test for the presence of the autoimmune markers mentioned previously.
These include GAD antibodies, insulin antibodies, and islet antibodies.
Once type 1 diabetes is diagnosed, insulin treatment begins immediately.
Initial treatment with insulin injections can provide a rest period for any beta cells that the immune system has yet to destroy.
These remaining cells may be able to produce enough insulin to keep blood sugar levels relatively stable for a period of weeks, months, or even years.
We refer to this as the “honeymoon phase” (or, more appropriately, “the calm before the storm”).
Eventually, however, beta cell function ceases almost completely, and insulin requirements go up and stay up.
The length of the honeymoon phase depends on a number of variables, but research has shown that early diagnosis (before most beta cells have been destroyed) and treatment leads to a prolonged honeymoon, as does a pattern of regular exercise.
Without insulin, a person with type 1 diabetes will become severely ketotic (have high levels of acids in the blood) and dehydrated, go into a coma, and die.
This is the reason type 1 diabetes is sometimes referred to as “insulin-dependent” diabetes: you depend on insulin to stay alive.
However, it is possible to have type 1 diabetes and also become insulin resistant, which, as you will see below, is the underlying cause of type 2 diabetes.
Those with type 1 diabetes who are insulin resistant must take insulin and incorporate appropriate lifestyle behaviors to achieve successful management.
Type 2 Diabetes (Chocolate)
Approximately 90 percent of people with diabetes have type 2 diabetes. Type 2 is very different from type 1 in that there is no autoimmune attack on the beta cells of the pancreas, and insulin production continues. In fact, in the early stages of type 2 diabetes, the pancreas may actually produce more insulin than usual.
There are typically three stages to type 2 diabetes: insulin resistance, followed by failure of the pancreas to meet the increased insulin need, followed by a reduction in pancreatic function. Let’s look at these stages one at a time.
Stage 1: The Resistance
In order to do its job of taking sugar out of the bloodstream and packing it into the body’s cells, insulin attaches to a receptor on the outer surface of the cell.
This is similar to the way a key enters a lock in order to open a door.
Once insulin attaches to the receptor, a “door” opens, and sugar molecules can enter the cell.
So for insulin to work, there have to be sufficient receptors on the cell surface, and the insulin must find and properly fit into the receptors.
Insulin resistance occurs when there are not enough receptors or the insulin has a hard time finding or fitting into them.
What causes insulin resistance? Typically, it is a combination of genetics (heredity) and lifestyle (the way we live). Having blood relatives (parents, siblings) with type 2 diabetes greatly increases the risk. Certain ethnic groups, including Native Americans and people of African, Hispanic, Asian, and Pacific Island descent, are also at high risk. The aging process plays a role as well. The older we get, the more insulin resistant we tend to become.
People who have polycystic ovary syndrome (PCOS) often become insulin resistant as a result of the overproduction of hormones that oppose insulin’s action. Likewise, hormones produced during pregnancy oppose insulin’s action and can lead to gestational diabetes.
A lack of physical activity can cause insulin resistance, as can stress.
That’s because we tend to produce insulin-resistance-inducing hormones during periods of illness, surgery, excitement, or emotional turmoil.
Steroid medications such as prednisone and cortisone also cause insulin resistance.
But the most widespread reason people become insulin resistant is weight gain.
Too much body fat, particularly around the middle, limits insulin’s ability to function properly.
In fact, gaining as little as ten pounds over a fifteen-year period can cause insulin resistance to double.
The most common reason for people to become insulin resistant is weight gain, specifically too much fat around the middle.
Obese individuals are seven times more likely to develop diabetes than those who maintain a healthy weight. And the problem is not restricted to adults: more than ever before, overweight children and teenagers are developing insulin resistance and type 2 diabetes.
Stage 2: The Production Shortfall
Insulin resistance affects a significant proportion of people worldwide. Why, then, do only a fraction of those with insulin resistance develop type 2 diabetes? The answer lies in the resiliency of the pancreas.
When insulin resistance occurs, the pancreas needs to produce more insulin to keep blood sugar levels in a normal range.
This is sort of like a business where one person isn’t doing their job, everyone else has to pick up the slack.
In most cases the pancreas can keep up with the added workload.
But not everyone’s pancreas has this capacity.
If the insulin resistance becomes too much for the pancreas to overcome, blood sugar levels rise above normal.
In other words, for type 2 diabetes to develop, you must have both insulin resistance and a pancreas that can’t keep up with the added workload.
To understand this concept better, imagine that you are an air conditioner trying to keep your house cool on a hot summer day.
If you’re one of those high-powered central air conditioning units that can crank out a bazillion BTUs, you’ll have no problem overcoming the warm outdoor weather and keeping the inside of the house cool.
But if you’re one of those rusty window units, you’re probably not going to be able to blow enough cold air to keep the entire house cool on really hot, humid days.
In this example, the heat and humidity are like insulin resistance: they present the challenge. The air conditioner is like the pancreas: an efficient system can overcome the challenge, but a lesser system will be unable to meet the challenge. You need both very hot and humid weather and a weak air conditioner to create a truly oppressive situation, backs of legs sticking to the furniture and all that.
At this early phase of type 2 diabetes, you can often get blood sugars back into a normal range through exercise (which reduces insulin resistance) and a diet designed to ease the flow of sugar into the bloodstream. Sometimes you can use oral medications or noninsulin injectable medications to help the pancreas (or insulin) work more effectively, and this may be all it takes. But it doesn’t usually stay that way forever.
Stage 3: Function Reduction
Type 2 diabetes is a progressive illness.
That is not a good thing.
There is nothing hip, cool, or modern about it.
It is progressive because it becomes harder to control as time goes on.
After you have diabetes for a number of years, your insulin resistance tends to grow worse, and your pancreas struggles to keep up with the huge demand for insulin.
Then a new problem sets in: just like an air conditioner that is forced to run full blast every minute of every day, the pancreas starts to break down. (Heck, if you were asked to work day after day without any breaks and no end in sight, you would break down too, or at least find a new job!)