Type 2 diabetes is a "silent" disease. Although you can feel thirsty, tired, hungry, or have frequent urination or blurry vision when blood sugar creeps into the danger zone, often there are no symptoms at all.

That's where home blood glucose monitoring comes in. There are two key elements to testing.

  • You prick your finger, get a drop of blood, and plug it into a glucose monitor (which can be purchased at any pharmacy). This tells you if your blood sugar is in the acceptable range.
  • You do something about it. After the test, you record the results (many monitors do this automatically) to discuss with your doctor. If your blood sugar is consistently too high, you should make changes in diet, exercise, or medication to keep blood sugar consistently in the "good" range. If it's too low (hypoglycemia), usually due to insulin or other medication, than you may need to consume glucose to bring it up.

Testing your blood sugar can show you that your medication is working, your diet is on track to control diabetes, and that you're not in danger from blood sugar that is too high or low.

Blood sugar fluctuates
In people without diabetes, the pancreas works a bit like the thermostat in your house.

Blood sugar is kept within a very narrow range, because the pancreas produces a continuous low level of insulin (which encourages muscles and the liver to absorb glucose) and bursts of insulin after you eat a meal.

After you eat carbohydrates (the type of food that has the biggest impact on blood sugar), blood sugar rises, peaks about an hour after you eat, and then falls back to baseline within two hours.

But in people with diabetes, insulin isn't doing its job, and blood sugar can rise to dangerous levels (it can be too high before you eat, after you eat, or both).

It's not just food that can affect blood sugar. It also rises in response to hormones released when you are stressed, sick, or injured.

Don't rely on hemoglobin A1C testing alone
If you rely solely on hemoglobin A1C tests, you'll never know if higher-than-normal test results are due to the plates of pasta, the stressful job promotion, a bout of the flu, or the fact that your diabetes is progressing and your medication is not doing its job.

That's why it's so important to test your blood sugar (though discuss with your doctor or diabetes educator how often you should be testing). If you're frequently monitoring, you should vary the time of day that you test. If blood sugar is too high first thing in the morning, it can mean something different from when it's too high after you eat or at night.

"If you test at the same time every day, you don't know how to manage your diabetes," says Donna Rice, immediate past president of the American Association of Diabetes Educators.

"Perhaps corn raises your blood sugar," she says. "You'd only know if you knew your level before a meal with corn, and after a meal with corn, and compared it with non-corn meals. That's the level of specificity that necessary for tight control."

And tight control—checking blood sugar and adjusting behavior or medicine—is necessary to prevent complications.

Last updated: Apr 03, 2008