More than 1 in 3 American adults have prediabetes, and 80% of them do not know it. Early detection through simple blood tests can change the trajectory entirely. This guide covers every diabetes screening test available, what the numbers mean, who should get tested, and how to order affordable lab work online — no doctor visit required.
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Browse Diabetes Tests at RequestATestUpdated March 31, 2026
Why It Matters
Diabetes is not a rare condition that happens to other people. According to the CDC, 38.4 million Americans have diabetes (about 11.6% of the population), and an additional 97.6 million adults have prediabetes. Combined, that is roughly 1 in 3 American adults living with some form of blood sugar dysregulation. The most alarming part: 8.7 million people with diabetes are undiagnosed, and the vast majority of those with prediabetes have no idea their blood sugar is elevated.
Type 2 diabetes develops gradually. For most people, the progression follows a predictable path: normal blood sugar gives way to insulin resistance, which leads to prediabetes, which eventually becomes full type 2 diabetes. This process typically unfolds over 5 to 10 years, and during much of that time, there are no obvious symptoms. You feel fine. Your energy is normal. Nothing hurts. Meanwhile, elevated blood sugar is silently damaging blood vessels, nerves, kidneys, and eyes.
By the time symptoms appear — increased thirst, frequent urination, blurred vision, slow-healing wounds, unexplained fatigue — the disease has often been present for years. At that point, some damage may already be irreversible. Diabetic retinopathy (eye damage), neuropathy (nerve damage), nephropathy (kidney damage), and significantly elevated cardiovascular risk all begin accumulating well before a clinical diagnosis.
This is precisely why screening matters so much. Catching prediabetes early gives you a window to reverse course. The landmark Diabetes Prevention Program (DPP) study demonstrated that modest lifestyle changes — losing 5–7% of body weight and getting 150 minutes of moderate exercise per week — reduced the risk of progressing from prediabetes to type 2 diabetes by 58%. That is more effective than medication. But you cannot act on information you do not have, and you do not get that information without a blood test.
Key fact: The CDC estimates that 97.6 million American adults — more than 1 in 3 — have prediabetes, and approximately 80% of them are unaware of it. Prediabetes produces no symptoms in most people. The only reliable way to detect it is through a blood test. If caught at this stage, progression to type 2 diabetes can often be prevented entirely through diet, exercise, and weight management.
Screening is simple, affordable, and widely available. A basic diabetes panel requires nothing more than a blood draw at a local lab — the same labs that handle cholesterol checks and routine physicals. In fact, A1C and fasting glucose are standard components of most comprehensive wellness panels, so you may be able to screen for diabetes as part of a broader health check. Results are typically available within 1 to 3 business days. Whether you go through your doctor, a community health center, or an online testing service, the tests are the same. The question is not whether to get screened — it is how soon you can get it done.
Available Tests
Several blood tests are used to screen for diabetes and assess blood sugar regulation. Each one measures something different, and understanding what they tell you helps you make informed decisions about which tests to order.
| Test | What It Measures | Fasting Required | Online Price |
|---|---|---|---|
| Hemoglobin A1C | Average blood sugar over 2–3 months | No | $29–$49 |
| Fasting Plasma Glucose (FPG) | Blood sugar after 8–12 hour fast | Yes | $29–$39 |
| Fasting Insulin | Insulin production when fasting | Yes | $39–$59 |
| HOMA-IR (calculated) | Insulin resistance index (from glucose + insulin) | Yes | Included with glucose + insulin |
| Oral Glucose Tolerance Test (OGTT) | Blood sugar response to glucose load over 2 hours | Yes | $49–$89 |
| Comprehensive Metabolic Panel (CMP) | Glucose + kidney, liver, electrolyte markers | Yes (for glucose) | $39–$59 |
The A1C test is the gold standard for diabetes screening and monitoring. It measures the percentage of hemoglobin in your red blood cells that has glucose attached to it. Because red blood cells live for approximately 120 days, the A1C reflects your average blood sugar over the past 2 to 3 months — giving you a broader picture than a single-point glucose reading.
One of the biggest practical advantages of the A1C test is that it does not require fasting. You can eat and drink normally before your blood draw, which makes scheduling significantly easier. This is one reason the ADA and CDC both recommend it as a primary screening tool.
| A1C Result | Classification | What It Means |
|---|---|---|
| Below 5.7% | Normal | Blood sugar regulation is healthy |
| 5.7% – 6.4% | Prediabetes | Elevated risk — lifestyle changes recommended |
| 6.5% or higher | Diabetes | Diagnostic threshold — follow up with healthcare provider |
Important note: Certain conditions can affect A1C accuracy, including iron-deficiency anemia, hemoglobin variants (common in people of African, Mediterranean, or Southeast Asian descent), recent blood loss or transfusion, and chronic kidney disease. If you have any of these conditions, your provider may rely more heavily on fasting glucose or OGTT for diagnosis.
The fasting glucose test measures the concentration of glucose in your blood after an 8 to 12 hour overnight fast. It provides a snapshot of your baseline blood sugar when your body has not recently processed any food. This test is inexpensive, widely available, and has been used for diabetes diagnosis for decades.
| Fasting Glucose Result | Classification | What It Means |
|---|---|---|
| Below 100 mg/dL | Normal | Fasting blood sugar is within healthy range |
| 100 – 125 mg/dL | Prediabetes (Impaired Fasting Glucose) | Blood sugar is elevated — monitor and take action |
| 126 mg/dL or higher | Diabetes | Confirmatory test recommended — consult provider |
The FPG test is straightforward and affordable but has one limitation: it captures only a single moment in time. Your blood sugar fluctuates throughout the day based on meals, stress, sleep, and physical activity. A one-time elevated reading should always be confirmed with a repeat test before a diagnosis is made. For this reason, many providers recommend combining an FPG with an A1C to get both a point-in-time measurement and a long-term average.
This test measures the amount of insulin your pancreas is producing while you are fasting. It is not part of the standard diagnostic criteria for diabetes, but it provides uniquely valuable information about what is happening beneath the surface — often years before glucose levels become abnormal.
Here is why that matters: in the early stages of insulin resistance, your pancreas compensates by producing more insulin to keep blood sugar in check. Your glucose levels may look completely normal on a standard test, but your insulin levels are already elevated — a sign that your body is working harder than it should to maintain normal blood sugar. This is the earliest detectable phase of metabolic dysfunction, and it is the phase where intervention is most effective.
Normal fasting insulin levels typically fall between 2.6 and 24.9 uIU/mL, though many functional and integrative medicine practitioners consider levels above 10 uIU/mL to be a warning sign of developing insulin resistance. Optimal fasting insulin is generally considered to be below 8 uIU/mL.
Why this test is underused: Standard diabetes screening typically relies on glucose-based tests (A1C and fasting glucose), which only become abnormal after insulin resistance has progressed significantly. A fasting insulin test can detect the problem at an earlier stage. If you want the most complete picture of your metabolic health, adding fasting insulin to your panel is one of the most informative upgrades you can make.
HOMA-IR (Homeostatic Model Assessment of Insulin Resistance) is not a separate blood draw — it is a calculated value derived from your fasting glucose and fasting insulin results using a simple formula: (fasting insulin x fasting glucose) / 405. Many labs and online testing services calculate it automatically when you order both fasting glucose and fasting insulin together.
HOMA-IR gives you a single number that estimates how resistant your cells are to the effects of insulin. Lower is better:
| HOMA-IR Score | Interpretation |
|---|---|
| Below 1.0 | Optimal insulin sensitivity |
| 1.0 – 2.0 | Early insulin resistance — worth monitoring |
| Above 2.0 | Significant insulin resistance — take action |
| Above 3.0 | Severe insulin resistance — high risk for type 2 diabetes |
HOMA-IR is increasingly recognized as one of the most useful markers for early metabolic disease detection. It quantifies a problem that standard glucose tests often miss until it has been developing for years. If you are ordering a diabetes screening panel and want to go beyond the basics, including fasting insulin (which allows HOMA-IR calculation) is the single most valuable addition.
The OGTT is the most involved of the standard diabetes tests. After an overnight fast, your blood is drawn to establish a baseline glucose level. You then drink a standardized glucose solution (75 grams of glucose), and your blood is drawn again at the 1-hour and 2-hour marks to measure how effectively your body processes the sugar load.
The OGTT is particularly good at detecting impaired glucose tolerance — a form of prediabetes where your fasting glucose may be normal but your body struggles to clear glucose after a meal. Some studies suggest the OGTT identifies up to 30% more cases of prediabetes and diabetes than fasting glucose alone.
| 2-Hour OGTT Result | Classification |
|---|---|
| Below 140 mg/dL | Normal glucose tolerance |
| 140 – 199 mg/dL | Prediabetes (Impaired Glucose Tolerance) |
| 200 mg/dL or higher | Diabetes |
The OGTT requires more time at the lab (approximately 2 to 2.5 hours total), which makes it less convenient than other options. It is most commonly used during pregnancy (gestational diabetes screening) or when other test results are borderline and a more definitive assessment is needed. For routine screening, the A1C and fasting glucose are generally preferred due to their simplicity.
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Risk Factors & Guidelines
The American Diabetes Association (ADA) and the CDC both publish screening guidelines that balance population-level risk with practical recommendations. Here is who should be getting tested, and how often.
The ADA recommends that all adults begin routine diabetes screening at age 35, regardless of other risk factors. If results are normal, repeat testing every 3 years. This recommendation was updated in 2022 — the previous threshold was age 45 — reflecting growing evidence that earlier detection improves outcomes. Adding an A1C to your annual blood test panel is one of the simplest ways to stay on top of this.
If your BMI is 25 or higher (23 or higher for Asian Americans) and you have one or more additional risk factors, screening should begin regardless of age. Excess weight, particularly around the midsection, is the single strongest modifiable risk factor for type 2 diabetes.
Women who developed diabetes during pregnancy have a 50% higher lifetime risk of developing type 2 diabetes. The ADA recommends testing every 1–3 years after delivery, continuing indefinitely. Many women are unaware of this elevated risk once the pregnancy is over.
If a previous test showed prediabetes (A1C 5.7–6.4%, fasting glucose 100–125 mg/dL), testing should increase to every 1 to 2 years to track whether your numbers are improving, stable, or progressing toward diabetes. This is the most important group to monitor closely.
The more risk factors you have, the more important screening becomes. If you identify with two or more of the following, consider getting tested regardless of your age:
Do not wait for symptoms. Type 2 diabetes is often called a "silent" disease because elevated blood sugar causes damage long before you feel anything. The classic symptoms — excessive thirst, frequent urination, blurred vision, slow wound healing — typically appear only after blood sugar has been significantly elevated for an extended period. Screening catches the problem years earlier, when it is most treatable and often reversible.
What to Order
Which tests you should order depends on where you are in the process. Someone who has never been tested needs a different panel than someone who is tracking known prediabetes or managing diagnosed diabetes. Here is how to think about it.
You have never been tested, or it has been more than 3 years since your last test.
You have been told you have prediabetes and want to track your progress.
If you have been diagnosed with type 2 diabetes, regular lab work is essential for tracking your control and watching for complications. The ADA recommends the following schedule:
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Understanding Your Results
The following table consolidates the diagnostic criteria established by the ADA. If your results fall in the prediabetes range on any test, you do not yet have diabetes — but your body is sending a clear signal that intervention is needed. If your results meet the diabetes threshold, a confirmatory test (repeat of the same test or a different test on a separate day) is recommended before a formal diagnosis is made.
| Test | Normal | Prediabetes | Diabetes |
|---|---|---|---|
| Hemoglobin A1C | Below 5.7% | 5.7% – 6.4% | 6.5% or higher |
| Fasting Plasma Glucose | Below 100 mg/dL | 100 – 125 mg/dL | 126 mg/dL or higher |
| OGTT (2-hour) | Below 140 mg/dL | 140 – 199 mg/dL | 200 mg/dL or higher |
| Random Plasma Glucose | Varies | N/A | 200 mg/dL or higher (with symptoms) |
Borderline results — values near the upper end of the normal range or at the low end of the prediabetes range — deserve attention, not dismissal. An A1C of 5.6% is technically "normal," but it is significantly different from an A1C of 5.0%. A fasting glucose of 98 mg/dL is within range, but it is trending in the wrong direction compared to 85 mg/dL.
If your results are in the high-normal or borderline range, consider ordering a fasting insulin test as well. Insulin levels often rise before glucose levels do, and an elevated fasting insulin with "normal" glucose is a clear early warning sign. This is where the HOMA-IR calculation becomes particularly valuable — it can detect metabolic dysfunction before standard screening criteria flag a problem.
One result does not define you. Diabetes is diagnosed based on confirmed, repeated abnormal results — not a single blood draw on a bad day. Stress, illness, medications, and sleep quality can all temporarily affect blood sugar. If your first result is abnormal, retest to confirm. If it is confirmed, take it seriously — but know that prediabetes is highly responsive to lifestyle intervention, and even early-stage type 2 diabetes can often be put into remission with sustained effort.
Cost Comparison
Cost should never be the reason you skip diabetes screening. Here is what you can expect to pay depending on where and how you get tested.
| Testing Option | Typical Cost | Includes | Wait Time for Results |
|---|---|---|---|
| Online Testing (RequestATest) Best Value | $29–$199 | Your choice of individual tests or panels, flat pricing | 1–3 business days |
| Primary Care Doctor | $150–$500+ | Office visit copay + lab fees (may be covered by insurance) | 3–7 days |
| Urgent Care | $100–$350+ | Visit fee + lab fees, limited test options | 1–5 days |
| Hospital Lab (Walk-in) | $200–$800+ | Hospital markup on lab fees, possible facility charges | 1–7 days |
| Community Health Center | $0–$100 (sliding scale) | Basic screening, income-based pricing | Varies |
The cost advantage of online ordering is significant. A basic A1C test through an online service runs $29–$49 with no additional fees. The same test ordered through a doctor typically costs $150 or more when you add the office visit copay — and that is with insurance. Without insurance, the markup can be even steeper. If you want a comprehensive diabetes panel (A1C + fasting glucose + fasting insulin), online pricing is typically $79–$149 compared to $300–$500+ through a traditional provider.
Online ordering is especially cost-effective for people who are monitoring prediabetes and need to test every 6 to 12 months. Scheduling a full doctor visit every time you need an A1C recheck is expensive and time-consuming when all you need is a blood draw and a number.
For more details on ordering lab work affordably, see our guide on lab test costs without insurance.
The Process
Ordering diabetes tests online is straightforward. The entire process — from placing your order to receiving results — typically takes 2 to 4 days. Here is what to expect at each step.
Visit the testing service website and choose the individual tests or diabetes panel you want. No doctor's referral or prescription is needed. For first-time screening, we recommend at minimum an A1C and fasting glucose. For a more complete assessment, add fasting insulin. Complete checkout and you will receive your lab requisition via email, typically within minutes.
If you ordered any fasting tests (fasting glucose, fasting insulin, OGTT), you will need to fast for 8 to 12 hours before your blood draw. Water is fine during the fast. Schedule a morning appointment so you can fast overnight and eat after your draw. If you only ordered an A1C, no fasting is required. Bring a photo ID and your lab requisition (printed or on your phone).
Walk into any participating Quest Diagnostics or LabCorp location — over 4,000 locations nationwide. Check in at the front desk, wait briefly, and a phlebotomist will draw your blood. The blood draw itself takes about 2 minutes. For a standard diabetes panel, a single blood draw is all that is needed (no urine sample required). Walk-ins are accepted at most locations.
Results are delivered to your secure online portal, typically within 1 to 3 business days. Each result includes the value, the reference range, and a clear normal/abnormal flag. You can download your results as a PDF, share them with your healthcare provider, or simply keep them for your own records. If you have questions about your results, many testing services offer physician consultation by phone.
Same labs, same tests, lower cost: Online testing services use the exact same CLIA-certified laboratories (Quest Diagnostics and LabCorp) as your doctor's office. The tests, equipment, and methodologies are identical. The only difference is who places the order and how you pay — online services offer flat, transparent pricing without the added cost of an office visit.
Testing Frequency
The right testing frequency depends on your current status and risk profile. Here are the evidence-based guidelines from the ADA and CDC.
Screen every 3 years starting at age 35. If your most recent A1C and fasting glucose are solidly normal (A1C below 5.4%, fasting glucose below 95 mg/dL), a 3-year interval is appropriate. Stay aware of changes in weight, activity level, or family history that might warrant earlier retesting.
Screen every 1 to 2 years. If you have one or more risk factors (family history, overweight, sedentary lifestyle, PCOS, high blood pressure) but your results are currently normal, more frequent monitoring is warranted. Annual testing with an A1C and fasting glucose is a reasonable approach.
Test every 6 to 12 months. This is the group that benefits most from regular monitoring. Tracking your A1C and fasting glucose over time tells you whether lifestyle changes are working. Adding fasting insulin and HOMA-IR every 6–12 months provides deeper insight into whether your insulin resistance is improving.
A1C every 3 to 6 months, plus annual comprehensive panels. If your diabetes is well-controlled and stable, an A1C every 6 months may be sufficient. If you have recently changed medications or are working to bring your numbers down, every 3 months gives you faster feedback. Comprehensive metabolic panels, lipid panels, and kidney function tests should be done at least annually.
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Common Questions
The A1C (hemoglobin A1C) test is widely considered the most practical screening test for diabetes because it reflects your average blood sugar over the past 2 to 3 months and does not require fasting. The ADA and CDC both recommend it as a primary screening tool. A fasting glucose test is also reliable and less expensive. For the most complete picture, many healthcare professionals recommend ordering both an A1C and a fasting glucose together, which provides both a long-term average and a point-in-time snapshot of your blood sugar regulation. If you want to detect insulin resistance at its earliest stage, adding a fasting insulin test gives you information that glucose-based tests alone will miss.
It depends on which test you are taking. The A1C test does not require fasting — you can eat and drink normally before the blood draw. The fasting plasma glucose (FPG) test requires an 8 to 12 hour fast, meaning no food or caloric beverages (water is fine and encouraged to stay hydrated for the blood draw). The oral glucose tolerance test (OGTT) also requires fasting. Fasting insulin and HOMA-IR tests are most accurate when fasting. If you are ordering multiple diabetes tests, the simplest approach is to schedule a morning appointment after an overnight fast so all results are accurate. If you only want an A1C, you can go at any time of day.
According to the ADA, an A1C of 6.5% or higher indicates diabetes. An A1C between 5.7% and 6.4% indicates prediabetes, meaning your blood sugar is higher than normal but has not yet reached the diabetes threshold. An A1C below 5.7% is considered normal. These thresholds are based on large-scale population studies correlating A1C levels with the risk of developing diabetic retinopathy and other complications. If your A1C comes back in the prediabetes range, this is actually valuable information — research shows that lifestyle changes at this stage can reduce the risk of progressing to type 2 diabetes by up to 58%. A single elevated A1C should be confirmed with a repeat test before a formal diagnosis.
Yes. Online lab testing services like RequestATest allow you to order diabetes screening tests directly, without a doctor's referral or prescription. You select the tests you want online, visit a local CLIA-certified lab (Quest Diagnostics or LabCorp) for a simple blood draw, and receive your results through a secure online portal within 1 to 3 business days. This is the same lab work your doctor would order — the same equipment, the same CLIA-certified lab, the same methodology. The only difference is that you are ordering it yourself and paying a flat, upfront price rather than billing through insurance. For more details, see our guide on ordering lab tests without a doctor.
Through an online testing service, individual diabetes tests typically cost between $29 and $79. An A1C test runs approximately $29 to $49, a fasting glucose test costs around $29 to $39, and a fasting insulin test is typically $39 to $59. Comprehensive diabetes panels that include multiple markers range from $79 to $199. By comparison, the same tests ordered through a doctor's office can cost $150 to $500 or more after the office visit copay, especially without insurance. Online ordering eliminates the office visit fee entirely, and the lab work itself is priced 30 to 70% lower than hospital or clinic pricing for the same tests at the same labs.
Prediabetes means your blood sugar levels are higher than normal but not yet high enough to be classified as type 2 diabetes. Specifically, prediabetes is defined as an A1C of 5.7 to 6.4%, a fasting glucose of 100 to 125 mg/dL, or an OGTT 2-hour result of 140 to 199 mg/dL. Diabetes is diagnosed when these values exceed those thresholds: A1C of 6.5% or higher, fasting glucose of 126 mg/dL or higher, or OGTT of 200 mg/dL or higher. The critical distinction is that prediabetes is reversible. With lifestyle changes — modest weight loss, regular physical activity, and dietary adjustments — many people can bring their blood sugar back to normal levels. Without intervention, approximately 15 to 30% of people with prediabetes develop type 2 diabetes within 5 years.
The ADA recommends diabetes screening every 3 years for all adults starting at age 35, or earlier and more frequently if you have risk factors such as being overweight, having a family history of diabetes, or belonging to a higher-risk ethnic group. If your results come back in the prediabetes range, testing should increase to every 1 to 2 years. People already diagnosed with prediabetes should test their A1C every 6 to 12 months to track whether lifestyle changes are working. Those with diagnosed diabetes should have an A1C checked every 3 to 6 months. If you have multiple risk factors but have never been tested, do not wait — order a screening now.
HOMA-IR (Homeostatic Model Assessment of Insulin Resistance) is a calculated index that estimates how resistant your cells are to insulin. It is derived from your fasting glucose and fasting insulin levels using the formula: (fasting insulin x fasting glucose) / 405. A HOMA-IR score below 1.0 is considered optimal, values between 1.0 and 2.0 suggest early insulin resistance, and scores above 2.0 indicate significant insulin resistance. HOMA-IR matters because insulin resistance is the underlying driver of type 2 diabetes and often develops years before blood sugar levels become abnormal. Your glucose and A1C can look completely normal while your HOMA-IR is already elevated, signaling that your pancreas is working overtime to maintain those normal numbers. Detecting insulin resistance early gives you the maximum window to reverse it through lifestyle changes before it progresses to prediabetes or diabetes.
Early detection is the most powerful tool against diabetes. A simple blood test can reveal whether your blood sugar is normal, trending toward prediabetes, or already at a level that needs attention. Order your diabetes screening online today — no doctor visit, no insurance, no waiting. Know your numbers so you can act on them.
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