Fasting blood sugar levels chart by age

You’ll need to get your blood sugar tested to find out for sure if you have prediabetes or type 1, type 2, or gestational diabetes. Testing is simple, and results are usually available quickly.

Tests for Type 1 Diabetes, Type 2 Diabetes, and Prediabetes

Your doctor will have you take one or more of the following blood tests to confirm the diagnosis:

A1C Test

The A1C test measures your average blood sugar level over the past 2 or 3 months. An A1C below 5.7% is normal, between 5.7 and 6.4% indicates you have prediabetes, and 6.5% or higher indicates you have diabetes.

Fasting Blood Sugar Test

This measures your blood sugar after an overnight fast (not eating). A fasting blood sugar level of 99 mg/dL or lower is normal, 100 to 125 mg/dL indicates you have prediabetes, and 126 mg/dL or higher indicates you have diabetes.

Glucose Tolerance Test

This measures your blood sugar before and after you drink a liquid that contains glucose. You’ll fast (not eat) overnight before the test and have your blood drawn to determine your fasting blood sugar level. Then you’ll drink the liquid and have your blood sugar level checked 1 hour, 2 hours, and possibly 3 hours afterward. At 2 hours, a blood sugar level of 140 mg/dL or lower is considered normal, 140 to 199 mg/dL indicates you have prediabetes, and 200 mg/dL or higher indicates you have diabetes.

Random Blood Sugar Test

This measures your blood sugar at the time you’re tested. You can take this test at any time and don’t need to fast (not eat) first. A blood sugar level of 200 mg/dL or higher indicates you have diabetes.

*Results for gestational diabetes can differ. Ask your health care provider what your results mean if you’re being tested for gestational diabetes.
Source: American Diabetes Association

If your doctor thinks you have type 1 diabetes, your blood may also tested for autoantibodies (substances that indicate your body is attacking itself) that are often present in type 1 diabetes but not in type 2 diabetes. You may have your urine tested for ketones (produced when your body burns fat for energy), which also indicate type 1 diabetes instead of type 2 diabetes.

Tests for Gestational Diabetes

Gestational diabetes is diagnosed using blood tests. You’ll probably be tested between 24 and 28 weeks of pregnancy. If your risk is higher for getting gestational diabetes (due to having more risk factors), your doctor may test you earlier. Blood sugar that’s higher than normal early in your pregnancy may indicate you have type 1 or type 2 diabetes rather than gestational diabetes.

Glucose Screening Test

This measures your blood sugar at the time you’re tested. You’ll drink a liquid that contains glucose, and then 1 hour later your blood will be drawn to check your blood sugar level. A normal result is 140 mg/dL or lower. If your level is higher than 140 mg/dL, you’ll need to take a glucose tolerance test.

Glucose Tolerance Test

This measures your blood sugar before and after you drink a liquid that contains glucose. You’ll fast (not eat) overnight before the test and have your blood drawn to determine your fasting blood sugar level. Then you’ll drink the liquid and have your blood sugar level checked 1 hour, 2 hours, and possibly 3 hours afterward. Results can differ depending on the size of the glucose drink and how often your blood sugar is tested. Ask your doctor what your test results mean.

Prevent Type 2 Diabetes

If your test results show you have prediabetes, ask your doctor or nurse if there is a lifestyle change program offered through the CDC-led National Diabetes Prevention Program in your community. You can also search for an online or in-person program. Having prediabetes puts you at greater risk for developing type 2 diabetes, but participating in the program can lower your risk by as much as 58% (71% if you’re over age 60).

Diabetes Treatment Plan

If your test results show you have type 1, type 2, or gestational diabetes, talk with your doctor or nurse about a detailed treatment plan—including diabetes self-management education and support services—and specific steps you can take to be your healthiest.

ISO Health Indicators Framework

UHC indicator GPW indicator

Rationale:

The expected values for normal fasting blood glucose concentration are between 70 mg/dL (3.9 mmol/L) and 100 mg/dL (5.6 mmol/L). When fasting blood glucose is between 100 to 125 mg/dL (5.6 to 6.9 mmol/L) changes in lifestyle and monitoring glycemia are recommended. If fasting blood glucose is 126 mg/dL (7 mmol/L) or higher on two separate tests, diabetes is diagnosed. An individual with low fasting blood glucose concentration (hypoglycemia) – below 70 mg/dL (3.9 mmol/L) – will experience dizziness, sweating, palpitations, blurred vision and other symptoms that have to be monitored. Increased fasting blood glucose concentration (hyperglycemia) is an indicator of a higher risk to diabetes. An individual’s fasting blood plasma glucose (FPG) may be in the normal range because the individual is not diabetic or because of effective treatment with glucose-lowering medication in diabetics. Mean FPG at the national level is used as a proxy for both promotion of healthy diets and behaviours and, treatment of diabetes.

Definition:

Mean fasting blood glucose of defined population in mmol/l. In adults 18 years and older and standardized by age. Yearly national estimates.

Method of measurement

Fasting plasma glucose (FPG) levels are determined by taking a blood sample from participants who have fasted for at least 8 hours. It can be measured in mmol/L or in mg/dL. For comparability, these values are converted in mmol/L. Other related biomarkers, such as haemoglobin A1c (HbA1c), can be used to help calculate national estimates.

Method of estimation:

For producing comparable national estimates, data observations based on mean FPG, oral glucose tolerance test (OGTT), HbA1c or combinations of these are all converted to mean FPG. A Bayesian hierarchical model is then fitted to these data to calculate age-sex-year-country specific prevalences, which accounts for national versus subnational data sources and urban versus rural data sources, and allows for variation in prevalence across age and sex. Age-standardized estimates are then produced by applying the crude estimates to the WHO Standard Population.Methodological details can be found here: https://www.who.int/diabetes/global-report/en/. Input data and methods are described here: NCD-RisC. Worldwide trends in diabetes since 1980: a pooled analysis of 751 population-based studies with 4·4 million participants. The Lancet; 2016. https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(16)00618-8/fulltext. UHC-related notes Estimates are calculated separately for men and women; for the UHC tracer indicator, a simple average of values for men and women is computed.

Preferred data sources:

Population-based surveys

Surveillance systems

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