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The glucose tolerance test (GTT) is a laboratory procedure designed to assess how well the body processes glucose, a vital sugar that serves as a primary energy source for cells. This test is particularly important in diagnosing conditions such as gestational diabetes, diabetes mellitus, and impaired glucose tolerance. It may also be utilized to evaluate lactose intolerance and malabsorption disorders. The test begins with the patient fasting for at least 8 hours to ensure accurate baseline measurements of blood glucose levels. A baseline blood sample is collected through venipuncture, which is a standard method for obtaining blood samples. Following this, the patient ingests a specified amount of concentrated glucose, typically 75 grams for non-pregnant individuals and 100 grams for pregnant patients, in the form of a drink known as Glucola. Subsequent blood samples are taken at designated intervals—60, 120, and 180 minutes post-ingestion—to monitor the body's glucose response. The plasma from these samples is analyzed using a quantitative enzymatic method to determine glucose levels. For testing related to lactose intolerance and malabsorption, a different protocol is followed, where a baseline sample is taken, and a 50-gram glucose dose is administered, with blood samples collected at 30, 60, 120, and 180 minutes. The first three blood samples collected during the GTT are reported using CPT® code 82951, while any additional samples beyond the initial three are reported using CPT® code 82952, which is specifically designated for each additional specimen collected during the test.
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The glucose tolerance test (GTT) is indicated for the following conditions:
The glucose tolerance test involves several key procedural steps to ensure accurate measurement of blood glucose levels:
After the glucose tolerance test is completed, patients may resume normal activities unless otherwise directed by their healthcare provider. It is important to monitor for any symptoms of hypoglycemia or hyperglycemia following the test. The results of the test will be reviewed by the physician to determine if further action is necessary, such as lifestyle modifications or additional testing. Patients should be informed about the importance of following up with their healthcare provider to discuss the results and any potential implications for their health.
| Short Descr | GTT-ADDED SAMPLES | Medium Descr | GLUCOSE TOLERANCE EA ADDL BEYOND 3 SPECIMENS | Long Descr | Glucose; tolerance test, each additional beyond 3 specimens (List separately in addition to code for primary procedure) | Status Code | Statutory Exclusion (from MPFS, may be paid under other methodologies) | Global Days | XXX - Global Concept Does Not Apply | PC/TC Indicator (26, TC) | 9 - Not Applicable | Multiple Procedures (51) | 9 - Concept does not apply. | Bilateral Surgery (50) | 9 - Concept does not apply. | Physician Supervisions | 09 - Concept does not apply. | Assistant Surgeon (80, 82) | 9 - Concept does not apply. | Co-Surgeons (62) | 9 - Concept does not apply. | Team Surgery (66) | 9 - Concept does not apply. | Diagnostic Imaging Family | 99 - Concept Does Not Apply | CLIA Waived (QW) | Yes | APC Status Indicator | Conditionally packaged laboratory tests | Type of Service (TOS) | 5 - Diagnostic Laboratory | Berenson-Eggers TOS (BETOS) | T1E - Lab tests - glucose | MUE | 3 | CCS Clinical Classification | 233 - Laboratory - Chemistry and Hematology |
This is an add-on code that must be used in conjunction with one of these primary codes.
| 82951 | MPFS Status: Statutory exclusion (from MPFS, may be paid under other methodologies) APC A PUB 100 CPT Assistant Article Glucose; tolerance test (GTT), 3 specimens (includes glucose) |
| 91 | Repeat clinical diagnostic laboratory test: in the course of treatment of the patient, it may be necessary to repeat the same laboratory test on the same day to obtain subsequent (multiple) test results. under these circumstances, the laboratory test performed can be identified by its usual procedure number and the addition of modifier 91. note: this modifier may not be used when tests are rerun to confirm initial results; due to testing problems with specimens or equipment; or for any other reason when a normal, one-time, reportable result is all that is required. this modifier may not be used when other code(s) describe a series of test results (eg, glucose tolerance tests, evocative/suppression testing). this modifier may only be used for laboratory test(s) performed more than once on the same day on the same patient. | 90 | Reference (outside) laboratory: when laboratory procedures are performed by a party other than the treating or reporting physician or other qualified health care professional, the procedure may be identified by adding modifier 90 to the usual procedure number. | QW | Clia waived test | 59 | Distinct procedural service: under certain circumstances, it may be necessary to indicate that a procedure or service was distinct or independent from other non-e/m services performed on the same day. modifier 59 is used to identify procedures/services, other than e/m services, that are not normally reported together, but are appropriate under the circumstances. documentation must support a different session, different procedure or surgery, different site or organ system, separate incision/excision, separate lesion, or separate injury (or area of injury in extensive injuries) not ordinarily encountered or performed on the same day by the same individual. however, when another already established modifier is appropriate it should be used rather than modifier 59. only if no more descriptive modifier is available, and the use of modifier 59 best explains the circumstances, should modifier 59 be used. note: modifier 59 should not be appended to an e/m service. to report a separate and distinct e/m service with a non-e/m service performed on the same date, see modifier 25. | Q5 | Service furnished under a reciprocal billing arrangement by a substitute physician or by a substitute physical therapist furnishing outpatient physical therapy services in a health professional shortage area, a medically underserved area, or a rural area | GA | Waiver of liability statement issued as required by payer policy, individual case | GY | Item or service statutorily excluded, does not meet the definition of any medicare benefit or, for non-medicare insurers, is not a contract benefit | GZ | Item or service expected to be denied as not reasonable and necessary | XU | Unusual non-overlapping service, the use of a service that is distinct because it does not overlap usual components of the main service |
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| 2011-01-01 | Changed | Add-on code status changed. Long description revised. Medium description changed. Guideline information changed. |
| 2010-01-01 | Changed | Code description changed. |
| Pre-1990 | Added | Code added. |
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