The diagnosis usually starts with tests that show whether your blood sugar level is normal or elevated. The most common test is done after an overnight fast. If your fasting blood sugar is consistently above 125 milligrams per deciliter (mg/dl), you have diabetes. Another test can assess your blood sugar at any time, even if you've just eaten. If that test shows you have blood sugar levels of 200mg/dl or above, you have diabetes. A third test measures the percentage of a blood protein called "hemoglobin A1c." (That's pronounced "A," "one," "c" and often abbreviated as HbA1c.) Here, the normal level is around 7 percent.

Over the past year, news reports have offered conflicting information about diabetes treatment. One major federal study found that patients who aimed to get their blood sugar down to a very low level actually had an increased risk of death. But then a second larger international study found no such risk. Despite the controversy over these findings, most doctors still think it's critical for patients to keep their blood sugar levels as close to normal as possible. They also agree that people who have diabetes alongside existing heart problems, high cholesterol and/or blood pressure need to be extra vigilant.

Because of the strong link between obesity and diabetes, some doctors recommend surgery to help people lose weight. Most procedures either restrict stomach size, interfere with food transit in the GI tract, or reduce fat absorption. The latest research shows that one procedure, gastric bypass, can help eliminate high blood sugar. But like nearly all surgery, the operation has many risks and so it's generally reserved for people who are very obese and who have long tried and failed to lose weight by other means. For most people, diabetes drugs and/or insulin are the preferred treatment.

From there, things get a little complicated. For starters, there are nine classes of medicines that are used to control type 2 diabetes. These include the hormone insulin and two other types of drugs that also must be injected. We didn't include those in our analysis. Rather, we focused on the six categories of pills that are often used as the first line of treatment (before insulin) and are commonly still prescribed even if insulin becomes necessary.

All of the pills lower blood sugar and improve the body's use of glucose. But they do so in different ways. That's important because if one type doesn't do the job, your doctor may suggest you take another medicine at the same time. Indeed, about one-third of people who start taking a diabetes drug will need another type of drug or insulin within six years.

You and your doctor will probably decide which drug or drugs to take based on a number of factors. These can include the severity of your diabetes (based on how high your blood sugar is), your HbA1c reading, any organ damage you may already have, your overall health status and other medical conditions, and which medicines you already take.