Compared with type 1 diabetes, type 2 is far more common, accounting for 90 to 95 percent of all cases of diabetes. It’s also far more complex.
High blood sugar is still the basic problem. But with type 2, the pancreas doesn’t completely shut off insulin production. Instead, the body’s use of insulin becomes impaired in any number of different ways:
- The beta cells of the pancreas are able to produce plenty of insulin, but they take their sweet time releasing it in response to the surge of glucose that follows a meal. Result: By the time the pancreas puts out the large amounts of insulin the body is waiting for, glucose levels have already built up in the blood.
- The number of beta cells is lower than normal, so the pancreas has trouble keeping up with insulin demand.
- There’s plenty of glucose and insulin, but cells don’t allow insulin to do its job — a condition known as insulin resistance. The problem can be caused by any number of things: A lack of proteins called insulin receptors on cells (think of insulin as a key and the receptor as a lock), a mismatch of insulin and receptors (the keys don’t fit the locks), or flaws in the chemistry that lets insulin pass into the cells. No matter what the problem, the result is the same: Glucose can’t get where it needs to go and stays in the bloodstream instead.
- Excess body weight boosts the need for insulin and the pancreas can’t keep up with demand.
Often, type 2 diabetes results from a combination of these factors, which tend to be interrelated. For example, obesity both creates more demand for insulin and promotes insulin resistance.
The major symptoms of type 2 diabetes mirror those of type 1, but type 2 is different in other ways:
It takes time. Unlike type 1, type 2 develops slowly over time, and symptoms don’t show up right away. When you finally notice that something’s wrong, you may already have had diabetes for years. That can make type 2 diabetes seem a bit vague — if it appears so gradually, when does it actually begin? And once you’re diagnosed, do you really, truly have it? Doctors admit that it’s sometimes tough to say exactly when any given case of diabetes got started — especially after the fact. But exact criteria based on blood-sugar levels clearly define when you have diabetes and when you don’t. Once you have it, you can control it to a remarkable degree, but it never goes away. There is no such thing as “a touch of” diabetes.
Adults suffer most. Type 2 diabetes is sometimes called adult-onset diabetes because it usually strikes after age 40 and is more likely to develop as you get older. One reason: Insulin resistance increases with age. In fact, more than 10 percent of people over age 60 have type 2 diabetes. But, as with other terms for diabetes, “adult onset” is becoming a misnomer because of the increasing prevalence of type 2 in kids.
Blood sugar is more stable. Because the pancreas still produces and releases at least some insulin when it’s needed, glucose levels in the blood don’t tend to swing as wildly as they do with type 1 — even though, on average, unmanaged blood-sugar levels with type 2 are still too high.