Blood sugar tests: Understanding your results

Introduction

Introduction

Blood sugar tests measure how well your body processes sugar (glucose). Some blood sugar tests are used to diagnose prediabetes or diabetes. Others determine how well you're managing your diabetes.

Click on the tabs to the left to learn more about various blood sugar tests and what the results mean.

Random blood sugar test

Random blood sugar test

What is a random blood sugar test?
A random blood sugar test measures your blood sugar at any point in time, not necessarily a certain amount of time after a meal, snack or beverage.

What's normal?
A normal random blood sugar level hasn't been clearly defined. However, even if you've recently eaten and your blood sugar level is at its peak, your random blood sugar level shouldn't be higher than 200 mg/dL.

What level suggests prediabetes?
If your random blood sugar level is higher than 140 mg/dL but lower than 200 mg/dL, you may have prediabetes.

What level suggests type 1 or type 2 diabetes?
A random blood sugar level higher than 200 mg/dL suggests either type 1 or type 2 diabetes. Remember, your blood sugar level alone isn't enough to differentiate between type 1 and type 2 diabetes. Your doctor may do other tests to determine which type of diabetes you have.

Glycated hemoglobin (A1C) test

Glycated hemoglobin (A1C) test

What is a glycated hemoglobin (A1C) test?
An A1C test, also known as a glycated hemoglobin test, isn't used for diagnosing prediabetes or diabetes. Instead, it gauges how well you're managing your diabetes.

Unlike a fasting blood glucose test or a daily finger stick, both of which measure your blood sugar level at a given time, the A1C test reflects your average blood sugar level for the past two to three months. Test results show what percentage of your hemoglobin — a protein found in red blood cells — is sugar coated (glycated).

What's normal?
The normal range for people without diabetes is 4 percent to 6 percent. An A1C level lower than 7 percent is a common target for people with diabetes — although your doctor may recommend a level lower than 6 percent if you're pregnant or have other health concerns. An A1C level higher than 7 percent may indicate the need for a change in your diabetes treatment plan.

The normal range for A1C results may vary somewhat among labs. If you consult a new doctor or use a different lab, it's important to consider this possible variation when interpreting your test results.

Diabetic nephropathy

Your kidneys contain millions of tiny blood vessels that filter waste from your blood and eliminate it in your urine. But diabetes can damage this delicate filtering system. In fact, diabetic nephropathy is the most common type of kidney failure — which is nearly always associated with high blood pressure. The high blood pressure can be treated with diet, exercise and medication. If your kidney function dips too low, you may need dialysis or a kidney transplant.

Hydronephrosis

In this condition, certain parts of one or both kidneys become plugged. This blocks urine flow and raises blood pressure. Some blockages resolve without treatment, but others require drainage or surgery. Once the blockage is removed, blood pressure often returns to normal.

Renovascular hypertension

This is a type of secondary hypertension caused by narrowing (stenosis) of one or both renal arteries. Renovascular hypertension can cause severe hypertension and irreversible kidney damage. It's often caused by the same type of fatty plaques that can damage your coronary arteries (atherosclerosis) or a condition in which the muscle and fibrous tissues of the renal artery wall thicken and harden into rings (fibromuscular dysplasia).

In mild cases, the high blood pressure may be treated with diet, exercise and medication while kidney function is simply monitored. In more severe cases, the doctor may open clogged arteries with a procedure known as angioplasty. Wire mesh tubes (stents) may be used to hold the arteries open. Another option is to surgically bypass blood flow around the affected arteries. Once blood flow to the kidneys improves, blood pressure usually returns to normal.

Kidney disease and high blood pressure can interact to create a variety of kidney problems, such as renovascular hypertension. The two main causes of this condition are atherosclerosis, which results in deposits of plaques in the arteries, and fibromuscular dysplasia, in which the muscle and fibrous tissues of the renal artery wall thicken and harden into rings.

Aldosteronism

In this condition, a tumor in the adrenal gland, increased growth of normal cells or other factors cause the adrenal glands to release an excessive amount of the hormone aldosterone. This makes your kidneys retain salt and water and lose too much potassium, which raises blood pressure. Treatment may include medication to block the action of aldosterone, surgery to remove a tumor in the adrenal gland, and diet, exercise and medication to treat the high blood pressure.

Hypothyroidism

This condition occurs when the thyroid gland doesn't produce enough thyroid hormone, which can cause high blood pressure. Hypothyroidism may have various causes, including inflammation, surgery, radiation treatment, certain medications or pituitary problems. Treatment with synthetic thyroid hormones usually returns blood pressure to normal.

Hyperparathyroidism

The parathyroid glands regulate levels of calcium and phosphorus in your body. If the glands secrete too much parathyroid hormone, the amount of calcium in your blood rises — which triggers a rise in blood pressure. Treatment is typically removal of the parathyroid glands, which returns blood pressure to normal.

Sleep apnea

In this condition, breathing repeatedly stops and starts during sleep. The repeated episodes of oxygen deprivation may damage the cellular lining of the blood vessel walls, which may deprive blood vessels of the elasticity they need to regulate blood pressure. Treating sleep apnea with a pressure mask, nasal devices, surgery, weight loss or other steps can help control the high blood pressure.

Preeclampsia

This common pregnancy complication, characterized by protein in the urine and elevated blood pressure, can develop after the 20th week of pregnancy. Left untreated, preeclampsia can lead to life-threatening complications for both mother and baby. The only cure for preeclampsia is delivery of the baby, which restores normal blood pressure.