Why Your Doctor Tests Your Blood Sugar

A screening blood sugar test is generally used to see if your blood sugar is high or low. High blood sugar may not always cause obvious symptoms. But it can be a sign of diabetes or prediabetes. Early diagnosis and treatment of type 2 diabetes is important in preventing problems.

Type 2 diabetes is on the rise in the United States. This can be controlled if more people pay attention to lifestyle choices. In general, Americans eat too much and exercise too little. Some long-term damage to the body may already be occurring in the prediabetes phase. This is especially true for the heart and circulatory system. In prediabetes, both the average and fasting blood sugars are above normal, but not quite in the range of diabetes. People with prediabetes are at high risk of developing type 2 diabetes. People with prediabetes can often prevent getting type 2 diabetes by making certain lifestyle changes. They can make changes in their diet, increase physical activity, and lose weight. Some people at a higher weight may also benefit from medicines to help prevent the development of type 2 diabetes.

Many people don't know what type 2 diabetes is or why doctors are interested in their blood sugar levels. The hormone insulin is made by your pancreas. Insulin allows your body to use sugar and other food for energy. Blood sugar rises when you don't have enough insulin. It also rises when your body's cells can't use what is there.

In type 2 diabetes, your pancreas either does not make enough insulin or your body's cells aren't able to use the insulin. This is called insulin resistance. Adults with diabetes are twice as likely to have a heart attack or stroke than those without it. High blood sugar also greatly raises the risk for kidney disease, blindness, amputation because of poor circulation, some types of cancer, and other problems.

The American Diabetes Association (ADA) advises type 2 diabetes screening for children and teens who are at a higher weight and have at least two of these risk factors:

• Family history of diabetes
• Being in a high-risk ethnic group
• Having signs of insulin resistance

It's always best to find diabetes before symptoms start. But watch for these symptoms:

• Severe tiredness (fatigue)
• Intense thirst
• Need to urinate often
• Sores that don't heal
• Weight loss when you aren't trying to lose weight
• Tingling or numbness in your feet or hands
• On-and-off blurry vision

The U.S. Preventative Services Task Force recommends adults ages 35 to 70 who are at a higher weight or have obesity should be screened for diabetes or prediabetes. The American Diabetes Association recommends all adults 35 years old and older should be screened for diabetes. If results are normal, testing should be repeated at least every 3 years, but may be repeated more often depending on initial results and risk status.

Risk factors for type 2 diabetes include:

• Being older than age 35.
• Being at a higher weight or having obesity. This means a body mass index of 25 or higher.
• Having parents or siblings who have diabetes.
• Having high blood pressure (140/90 mmHg or higher in adults).
• Having HDL ("good") cholesterol of less than 35 mg/dL.
• Having a triglyceride level of 250 mg/dL or higher.
• Getting little exercise.
• Having a high-risk ancestry or ethnicity. This includes African American, Alaska Native, Hispanic American, Native American, Asian American, and Pacific Islander.
• Having a blood sugar test in the past that was high.
• Having a history of gestational diabetes.
• Having polycystic ovarian syndrome (PCOS).
• Having a history of heart disease.

The ADA now advises the A1C test to help diagnose prediabetes and diabetes. The A1C gives an average blood glucose level for the past 3 months. An A1C level below 5.7% is considered normal. An A1C of 6.5% or above shows diabetes. A1C in prediabetes is generally between 5.7% and 6.4%.

The A1C test is not more accurate than the fasting plasma glucose test and the 2-hour oral glucose tolerance test. The difference is the AIC test doesn't require fasting. It can be measured at any time of the day.

Experts hope the ease of the A1C will result in more testing for people who are at risk for diabetes or prediabetes. This would help reduce the number of people with undiagnosed diabetes in the U.S.