Type 2 diabetes is caused by two main metabolic problems: one of those problems is that the body is not making enough insulin (the hormone that controls blood sugar.) The other metabolic problem is that the body is not responding to insulin very well – it’s called insulin resistance. Even when insulin is present, the body just doesn’t react very well.
When someone has diabetes, what that means is that their blood sugar is too high – that’s what defines diabetes. Really, though, diabetes is a spectrum of disease because there’s a lot of ways to get blood sugar that’s too high. On the one hand, we have classic type 2 diabetes where people are making plenty of insulin (the hormone that controls blood sugar) but they don’t respond to it very well. They’re resistant to it, so they have high blood sugar. On the other end of the spectrum, you have type 1 diabetes. In that type of diabetes, people are making no insulin at all. They are very sensitive to it and respond to it but they don’t make it, so they have diabetes. In between these two spectrums, you have a lot of other things that contribute to the development of high blood sugar. You have certain medications that cause diabetes, certain illnesses and other medical problems that can cause it – so there’s a lot of overlap sometimes between the conditions and you can’t always tell if it’s type 1 or type 2.
We have a lot of great evidence that type 2 diabetes in even (or even most) people can be prevented with lifestyle modification. Since type 2 diabetes is so closely associated with obesity or being overweight, we know that if you reduce your body weight and maintain a healthy body weight, most people won’t get type 2 diabetes. We have a lot of research over the years that being more physically active, caloric restriction, making healthy food choices – all of those things that lead to weight reduction also reduce the onset of type 2 diabetes in high-risk people. There are also certain medications that can prevent type 2 diabetes in high-risk people. The most common one is called Metformin and there is excellent data that shows that certain people with a risk for type 2 diabetes can reduce that risk by taking Metformin.
Because people with diabetes often have no symptoms at all, it’s important for people to be tested for diabetes. Anyone with a diabetes risk factor needs to be tested. It’s currently estimated that about 1 out of 3 people with diabetes don’t even know they have it. You can’t be treated well if you don’t know you have it. If you have a risk factor (age over 45, being overweight, having hypertension, having abnormal cholesterol, having heart disease, having a large baby, having gestational diabetes, having certain conditions like polycystic ovarian disease, etc.) you should get a test. The test can be ordered by your primary care physician. It is a blood test in most cases and it’s really easy. The most common test right now is a blood test called Hemoglobin A1c that can be tested without having to fast – we test it at any time. Sometimes people will use a fasting glucose but you have to fast for that. There’s another test called an Oral Glucose Tolerance Test that takes a lot of time. We don’t use that a lot anymore but sometimes (especially pregnant women) will be tested for diabetes by an Oral Glucose Tolerance Test. What that means is someone goes to the lab, drinks some sweet sugary stuff, and their blood sugar is checked about two hours later.
In the United States, about 1 in 11 or 1 in 12 people have diabetes. The most common kind of diabetes is type 2 diabetes – which represents about 90-95% of all cases. Even though about 1 in 11 or 12 people have it, that statistic changes a lot depending on your risk factors for diabetes. For any given person or population, the prevalence might be much higher.
In the last few decades, we’ve learned a lot about what causes diabetes and the complications associated with diabetes. For example, we’re very confident that if we reduce the blood sugar and keep it as normal as possible, we’ll reduce eye, kidney, and nerve disease associated with diabetes. Unfortunately, in order to reduce heart attacks and strokes that are associated with diabetes, we have to do something other than just controlling the blood sugar. We have to aggressively target cardiovascular risk factors. Some of the research that’s going on right now is to find out if any particular strategy of blood sugar lowering is better than the others at reducing heart attacks and strokes. A couple of diabetes drugs have been approved for reducing heart disease – even in non-diabetes. That’s a big deal in diabetes research right now – is what particular strategy do we need to do to reduce the complications? It’s pretty clear that it’s not just lowering the blood sugar – how we’re lowering the blood sugar might make a difference. We’re learning more about that every year.
Unfortunately, we don’t have a cure for type 1 diabetes. We’re still looking hard but at this point, we don’t have a cure. On the other hand, with type 2 diabetes we do have a cure for most people: diet and exercise. Most of the increase in the prevalence of diabetes that we’ve seen in the past few decades are directly associated with obesity. Most people with type 2 diabetes can make the disease go away or at least make it less severe if they maintain a healthy body weight.