Glucose, Plasma

Single-analyte tests

• Glucose Tolerance Test, 2 Specimens (75g) 35181

  Plasma · Fasting required

  Method and collection

  Method

  Spectrophotometry (SP)

  Preparation

  Fasting required. Fasting is defined as no consumption of food or beverage other than water for at least 8 hours before specimen collection.

  Collection

  Immediately after a fasting specimen is obtained, have patient ingest a 75 g load of glucose. Draw subsequent specimen 2 hours later. Label each specimen with the specific draw time. Note: Serum and plasma submissions must be separated from cells.

  Reference notes

  American Diabetes Association Diagnostic Criteria for Diabetes Mellitus Glucose Value (mg/dL) Interpretation | Fasting | 2-Hr Tolerance Normal | <100 | <140 Impaired Fasting | 100-125 Impaired Tolerance | | 140-199 Diabetes | ≥126* | ≥200* *Must be confirmed by testing on a subsequent day.

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• Glucose Tolerance Test, 3 Specimens (75g) 23475

  Plasma · Fasting required

  Method and collection

  Method

  Spectrophotometry (SP)

  Preparation

  Fasting required. Fasting is defined as no consumption of food or beverage other than water for at least 8 hours before testing.

  Collection

  Immediately after a fasting specimen is obtained, have patient ingest a 75 g load of glucose. Draw subsequent specimens 1 and 2 hours later. Label each with the specific draw time. Serum and plasma submissions must be separated from cells.

  Reference notes

  American Diabetes Association Diagnostic Criteria for Diabetes Mellitus Glucose Value (mg/dL) Interpretation | Fasting | 1-Hr Tolerance | 2- Hr Tolerance Normal | <100 | Not Established | <140 Impaired Fasting | 100-125 Impaired Tolerance | | | 140-199 Diabetes | ≥126* | | ≥200* *Must be confirmed by testing on a subsequent day.

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• Glucose Tolerance Test, 4 Specimens 10559

  Plasma · Fasting required · Turnaround Set up: Mon-Sat; Report available: 3 days

  Method and collection

  Method

  Spectrophotometry (SP)

  Preparation

  Fasting required. Fasting is defined as no consumption of food or beverage other than water for at least 8 hours before testing.

  Collection

  Immediately after a fasting specimen is obtained, have patient ingest a 75 g load of glucose. Draw subsequent specimens per physician's order. If not specified by the physician, draw specimens 1, 2 and 3 hours later. Label each with the specific draw time. Note: Serum and plasma submissions must be separated from cells

  Reference notes

  American Diabetes Association Diagnostic Criteria for Diabetes Mellitus Glucose Value (mg/dL) Interpretation | Fasting | 1 Hr Tolerance | 2 Hr Tolerance Normal | <100 | Not established | <140 Impaired Fasting | 100-125 Impaired Tolerance | | | 140-199 Diabetes | ≥126* | | ≥200* *Must be confirmed by testing on a subsequent day. Specimen 1: 65-99 mg/dL

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• Glucose Tolerance Test, 5 Specimens 10560

  Plasma · Fasting required

  Method and collection

  Method

  Spectrophotometry (SP)

  Preparation

  Fasting required. Fasting is defined as no consumption of food or beverage other than water for at least 8 hours before testing.

  Collection

  Immediately after a fasting specimen is obtained, have patient ingest a 75 g load of glucose. Draw subsequent specimens per physician's order. If not specificed by the physician, draw specimens 1, 2, 3 and 4 hours later. Label each with the specific draw time. Note: Serum and plasma submissions must be separated from cells

  Reference notes

  American Diabetes Association Diagnostic Criteria for Diabetes Mellitus Glucose Value (mg/dL) Interpretation | Fasting | 1 Hr Tolerance | 2 Hr Tolerance Normal | <100 | Not established | <140 Impaired Fasting | 100-125 Impaired Tolerance | | | 140-199 Diabetes | ≥126* | | ≥200* *Must be confirmed by testing on a subsequent day. Specimen 1: 65-99 mg/dL

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• Glucose Tolerance Test, 6 specimens 10562

  Plasma · Fasting required

  Method and collection

  Method

  Spectrophotometry (SP)

  Preparation

  Fasting required. Fasting is defined as no consumption of food or beverage other than water for at least 8 hours before testing.

  Collection

  Immediately after a fasting specimen is obtained, have patient ingest a 75 g load of glucose. Draw subsequent specimens per physician's order. If not specified by the physician, draw specimens 1, 2, 3, 4 and 5 hours later. Label each with the specific draw time. Serum and plasma submissions must be separated from cells.

  Reference notes

  American Diabetes Association Diagnostic Criteria for Diabetes Mellitus Glucose Value (mg/dL) Interpretation Fasting 1 Hr Tolerance 2 Hr Tolerance Normal <100 Not established <140 Impaired Fasting 100-125 Impaired Tolerance 140-199 Diabetes ≥126* ≥200* *Must be confirmed by testing on a subsequent day. Specimen 1: 65-99 mg/dL

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• Glucose Tolerance Test, 7 Specimens 10563

  Plasma · Fasting required

  Method and collection

  Method

  Spectrophotometry (SP)

  Preparation

  Fasting required. Fasting is defined as no consumption of food or beverage other than water for at least 8 hours before testing.

  Collection

  Immediately after a fasting specimen is obtained, have patient ingest a 75 g load of glucose. Draw subsequent specimens per physician's order. If not specified by the physician, draw specimens 1, 2, 3, 4, 5 and 6 hours later. Label each with the specific draw time. Serum and plasma submissions must be separated from cells.

  Reference notes

  American Diabetes Association Diagnostic Criteria for Diabetes Mellitus Glucose Value (mg/dL) Interpretation Fasting 1 Hr Tolerance 2 Hr Tolerance Normal <100 Not established <140 Impaired Fasting 100-125 Impaired Tolerance 140-199 Diabetes ≥126* ≥200 ≥200* *Must be confirmed by testing on a subsequent day.

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• Glucose Tolerance Test, Gestational, 3 Specimens (75g) 18927

  Plasma · Fasting required

  Method and collection

  Method

  Spectrophotometry (SP)

  Preparation

  Fasting required. Fasting is defined as no consumption of food or beverage other than water for at least 8 hours before testing.

  Collection

  Immediately after a fasting specimen is obtained, have patient ingest a 75 g load of glucose. Draw subsequent specimens 1 and 2 hours later. Label each with the specific draw time. Serum and plasma submissions must be separated from cells.

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• Glucose Tolerance Test, Gestational, 4 Specimens (100g) 6745

  Plasma · Fasting required · Turnaround Set up: Mon-Sat; Report available: 3 days

  Method and collection

  Method

  Spectrophotometry (SP)

  Preparation

  Fasting required. Fasting is defined as no consumption of food or beverage other than water for at least 8 hours before testing.

  Collection

  Immediately after a fasting specimen is obtained, have patient ingest a 100 g load of glucose. Draw subsequent specimens 1, 2 and 3 hours later. Label each with the specific draw time. Serum and plasma submissions must be separated from cells.

  Reference notes

  Glucose, Fasting 65-94 mg/dL Glucose, 1-Hour <180 mg/dL Glucose, 2-Hour <155 mg/dL Glucose, 3-Hour <140 mg/dL

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• Glucose Tolerance Test, Gestational, 4 Specimens (100g) with NDDG 16292

  Plasma · Fasting required

  Method and collection

  Method

  Spectrophotometry (SP)

  Preparation

  Fasting required. Fasting is defined as no consumption of food or beverage other than water for at least 8 hours before testing.

  Collection

  Immediately after a fasting specimen is obtained, have patient ingest a 100 g load of glucose. Draw subsequent specimens 1, 2 and 3 hours later. Label each with the specific draw time. Serum and plasma submissions must be separated from cells.

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• Glucose, Fasting and Gestational, 135 Cutoff 1430

  Plasma · Fasting required

  Method and collection

  Method

  Spectrophotometry (SP)

  Preparation

  Fasting required. Fasting is defined as no consumption of food or beverage other than water for at least 8 hours before testing.

  Collection

  Immediately after a fasting specimen is obtained, have patient ingest a 50 g load of glucose. Draw subsequent specimen 1 hour later. Label each specimen with the specific draw time. Serum and plasma submissions must be separated from cells. Note: The test should be performed between weeks 24 and 28 of gestation.

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• Glucose, Fasting and Gestational, 140 Cutoff 19834

  Plasma · Fasting required

  Method and collection

  Method

  Spectrophotometry (SP)

  Preparation

  Fasting required. Fasting is defined as no consumption of food or beverage other than water for at least 8 hours before testing

  Collection

  Immediately after a fasting specimen is obtained, have patient ingest a 50 g load of glucose. Draw subsequent specimen 1 hour later. Label each specimen with the specific draw time. Note: The test should be performed between weeks 24 and 28 of gestation. Serum and plasma submissions must be separated from cells.

  Reference notes

  Glucose, Plasma | 65-99 mg/dL Glucose, Gestational Screen (50g)-140 cutoff | <140 mg/dL

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• Glucose, Fasting and Postprandial/2-Hour 6881

  Plasma · Fasting required

  Method and collection

  Method

  Spectrophotometry (SP)

  Preparation

  Fasting required. Fasting is defined as no consumption of food or beverage other than water for at least 8 hours before testing.

  Collection

  First specimen obtained fasting. Second specimen obtained 2 hours following a meal. Label each specimen with the specific draw time. Serum and plasma submissions must be separated from cells.

  Reference notes

  Glucose, Plasma 65-99 mg/dL Glucose, Postprandial/2-Hour <140 mg/dL

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• Glucose, Plasma 484

  Plasma · Fasting required · Turnaround Set up: Mon-Sat; Report available: 3 days

  Method and collection

  Method

  Spectrophotometry (SP)

  Preparation

  Fasting required. Fasting is defined as no consumption of food or beverage other than water for at least 8 hours before testing.

  Collection

  Serum and plasma submissions must be separated from cells

  Reference notes

  65-99 mg/dL

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Panels that include this biomarker

• Lactose Tolerance Test, 5 Specimens (50g) 7675

  2 analytes · Plasma · Fasting required · Turnaround Set up: Mon-Sat; Report available: 3 days

  Method and collection

  Method

  Spectrophotometry (SP)

  Preparation

  Note: This cannot be performed at a patient service center because of the preparation step required for the lactol solution. Fasting required. Fasting is defined as no consumption of food or beverage other than water for at least 8 hours before testing.

  Collection

  Obtain fasting specimen. Immediately after fasting specimen is obtained, have the patient ingest a 50 g dose of lactose (obtained through client supply). Collect subsequent specimens 1/2, 1, 2, and 3 hours, labeling each sample at the time of draw with the specific draw time. LacTest Preparation instructions: If using LacTest, dissolve two 25 g packets into 6-8 oz of water to make the 50 g dose required. Mix thoroughly. Because of the relative insolubility of lactose, mix frequently during ingestion as necessary. If any lactose precipitate remains in the glass, swirl with a small amount of additional water and drink. For pediatric use, dissolve 1 gram of LacTest for every 1 kg (2.2 lbs) of the patient's body weight in 6-8 oz of water.

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Single-analyte tests

• Glucose, Plasma 001818

  Plasma · Fasting not stated · Turnaround Within 1 day

  Method and collection

  Method

  Enzymatic

  Preparation

  Blood should be drawn in the morning after an overnight fast. Per the American Diabetes Association (ADA), fasting is defined as no caloric intake for at least eight hours.1

  Collection

  Separate plasma within 45 minutes of collection. Only gray-top tubes may be submitted without centrifugation. Label specimen as plasma. Mix well.

  Reference notes

  70−99 mg/dL • Prediabetes: 100–125 mg/dL • Diabetes: >125 mg/dL

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Panels that include this biomarker

• Diabetes Risk–Asymptomatic Adults 090400

  2 analytes · Plasma · Fasting not stated · Turnaround Within 1 day

  Method and collection

  Method

  A1c: Roche Tina-Quant Hemoglobin A1c which is NGSP certified and standardized to the DCCT reference assay. Plasma glucose: enzymatic

  Preparation

  A1c: None FPG: Blood should be drawn in the morning after an overnight fast (no caloric intake for at least eight hours), during which time the individual may consume water.

  Collection

  Hemoglobin A1c: The usual precautions in the collection of venipuncture samples should be observed. The sample must be free of clots. Samples with any hematocrit disorders can lead to erroneous results. Send the entire tube to the laboratory. FPG: Label specimen as plasma. Mix well.

  Reference notes

  Hemoglobin (Hb) A1c (%) Fasting Plasma Glucose mg/dL Diabetes | >6.4 | >125 Prediabetes | 5.7–6.4 | 100–125 Glycemic Control for Adults with Diabetes | <7.0 | N/A Normal | 4.8–5.6 | 70–99 For selected individual patients, providers might reasonably suggest even lower A1c goals than the general goal of <7%, if this can be achieved without significant hypoglycemia or other adverse effects of treatment. Such patients might include those with short duration of diabetes, long life expectancy, and no significant CVD. Conversely, less‐stringent A1c goals than the general goal of <7% may be appropriate for patients with a history of severe hypoglycemia, limited life expectancy, advanced microvascular or macrovascular complications, and extensive comorbid conditions and those with long-standing diabetes in whom the general goal is difficult to attain.

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• Gestational Glucose Tolerance Screening and Diagnostic Test (Two-hour, ADA Recommendations) 101000

  2 analytes · Serum · Fasting not stated · Turnaround Within1 day

  Method and collection

  Method

  Enzymatic

  Preparation

  Patient should be active and eat a regular diet that includes at least 150 grams of carbohydrate daily for three days prior to the test. The patient should be instructed not to eat or drink anything except water for at least eight hours and not more than 14 hours before the test. Patients should also be advised to discontinue, whenever possible, all nonessential medication that can affect glucose metabolism at least three days before testing.

  Collection

  Draw a fasting blood sample before administering glucose. Administer a 75-gram glucose and draw blood after one hour and two hours. The patient should remain seated throughout the test. Submit 1 mL serum or plasma for fasting, one-hour, and two-hour specimens. Separate serum or plasma from cells within 45 minutes of venipuncture. Gray-top tubes only, may be submitted without centrifugation. Label each tube with the patient's name and collection time interval (i.e,, fasting, one-hour, and two-hour).

  Reference notes

  See table. Specimen (Two-hour GGT Test)* Range (mg/dL) *A positive diagnosis requires that only one of the high thresholds be exceeded. Fasting 70−91 One-hour 70−179 Two-hour 70−152

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• Glucose Tolerance Test (GTT), Two-hour (Oral WHO Protocol) 101200

  2 analytes · Serum · Fasting not stated · Turnaround Within1 day

  Method and collection

  Method

  Enzymatic

  Preparation

  Patient should be active and eat a regular diet that includes at least 150 grams of carbohydrate daily for three days prior to the test. Patient should be instructed not to eat or drink anything except water for at least eight hours and not more than 14 hours before the test. Patients should also be advised to discontinue, whenever possible, all nonessential medication that can affect glucose metabolism at least three days before testing.

  Collection

  Draw a fasting blood sample before administering glucose. Administer a 75-gram glucose and draw blood after two hours. The patient should remain seated throughout the test. Submit 1 mL serum or plasma for fasting and two-hour specimens. Separate serum or plasma from cells within 45 minutes of venipuncture. Gray-top tubes only, may be submitted without centrifugation. Label each tube with the patient's name and collection time interval. (ie, fasting and two-hour).

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• Gestational Glucose Tolerance Diagnostic Test (Three-hour, ACOG Recommendations) 102004

  4 analytes · Serum · Fasting not stated · Turnaround Within 1 day

  Method and collection

  Method

  Enzymatic

  Preparation

  For three days prior to the test, patients should eat an unrestricted diet of 150 or more grams of carbohydrate and be permitted unrestricted physical activity. Patients should be instructed to eat and drink nothing except water for at least eight hours and not more than 14 hours before the test. Patients should also be advised to discontinue, whenever possible, all nonessential medication that can affect glucose metabolism at least three days before testing.

  Collection

  Draw a fasting blood sugar before administering 100-gram glucose, and draw blood at one, two, and three hours. The subject should remain seated and not smoke throughout the test. Submit 1 mL serum or plasma for fasting, one-hour, two-hour, and three-hour specimens. Separate serum or plasma from cells within 45 minutes of venipuncture. Gray-top tubes only, may be submitted without centrifugation. Label each tube with patient's name and collection time interval (i.e., fasting, one-hour, two-hour, and three-hour).

  Reference notes

  See table. Specimen* Plasma or Serum Glucose Level (Carpenter and Coustan Conversion) Plasma Glucose Level (National Diabetes Data Group Conversion) *The diagnosis of GDM can be made based on the result of the 100-gram, three-hour oral glucose tolerance test, for which there is evidence that treatment improves outcome. Either the plasma or serum glucose level established by Carpenter and Coustan or the plasma level designated by the National Diabetes Data Group is appropriate to use. A positive diagnosis requires that two or more high thresholds be exceeded. The Carpenter and Coustan conversion is used to establish Labcorp reference intervals. Fasting 70−94 mg/dL 70−105 mg/dL One-hour 70−179 mg/dL 70−190 mg/dL Two-hour 70−154 mg/dL 70−165 mg/dL Three-hour 70−139 mg/dL 70−145 mg/dL

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