Test Details
Methodology
Roche Tina Quant; enzymatic
Result Turnaround Time
3 - 10 days
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Use
GlycoMark® testing provides an estimate of the patient's postmeal glucose during a one- to two-week period, making it ideal for intermediate term monitoring of glycemic control in diabetic patients. GlycoMark® testing can also help to monitor the effectiveness of therapeutics targeting postprandial glucose (PPG),1,2 and is a useful adjunct to routine A1c testing, because it responds more rapidly and sensitively to hyperglycemia than A1c.1,2
Hb A1c testing provides an estimate of the patient's average blood glucose over a period of two to three months. Hb A1c testing helps assess the long term diabetic control for individuals with diabetes mellitus.
Limitations
Individuals using INVOKANA® may demonstrate low levels of 1,5-AG. 1,5-AG blood levels are falsely lowered by the diabetes drug INVOKANA®, which prevents reabsorption of 1,5-AG in the kidneys. INVOKANA® belongs to new class of diabetes medication known as sodium-glucose cotransporter 2 (SGLT2) inhibitors, which block reabsorption of glucose in the kidneys, and other SGLT2 inhibitors may have the same effect. INVOKANA® is a trademark of Janssen Pharmaceuticals, Inc.
Persistently positive urinary glucose levels, or oxyhyperglycemia after gastrectomy, may result in a low 1,5-AG value. Low values have also been observed in pregnancy, terminal stage renal failure, dialysis patients, advanced cirrhosis, and prolonged incapability of oral ingestion of food. Abnormal values have also been noted in individuals with abnormal glomerular filtration rates.3,4
For some patients with severe hyperglycemia, the internal pool of 1,5-AG may tend to remain depleted as a result of persistent glucosuria. In these cases, measurements of 1,5-AG may be less indicative of initial recovery following initiation of antidiabetic treatment.
1,5-AG values may be increased when some Chinese medicines, such as Polygala tenuifolia and senega syrup, are administered. Values may also be increased during intravenous hyperalimentation. 1,5-AG values may be lower in patients undergoing therapy with steroids.5
Some α-glucosidase inhibitors, such as acarbose, may potentially reduce 1,5-AG levels due to interference with intestinal absorption of 1,5-AG.
As with all diagnostic tests, GlycoMark® results should be interpreted along with clinical findings and results from other diagnostic methods.
Custom Additional Information
1,5 Anhydroglucitol (1,5-AG) is a naturally occurring monosaccharide found in nearly all foods. Individuals without diabetes and those with diabetes but have well-controlled blood glucose levels <180 mg/dL have detectably high levels of 1,5-AG. When a individual's glucose levels are in a normal range, 1,5-AG is naturally processed by the kidneys and nearly all of it is reabsorbed back into the blood stream by the renal proximal tubules. Individuals with diabetes that have blood glucose level excursion in excess >180 mg/dL can be expected to have low levels of 1,5-AG. In these individuals, excess glucose in the body is reabsorbed first by the kidneys, blocking 1,5-AG reabsorption. The body is unable to maintain a high steady state level of 1,5-AG in blood and tissues.
• Normal or high GlycoMark® values = Normal blood glucose levels
• Low GlycoMark® values = Elevated blood glucose levels or high blood glucose spikes.
• Normal levels of glucose produce a normal amount of Hb A1c. As the average amount of plasma glucose increases, the fraction of Hb A1c increases in a predictable way. This test serves as an indicator for average blood glucose levels over the previous two to three months prior to the measurement.
• Normal Hb A1c values = Normal blood glucose
• Higher Hb A1c values = Elevated blood glucose levels
Specimen Requirements
Specimen
Whole blood and serum or plasma
Volume
3 mL whole blood and 1 mL serum or plasma
Minimum Volume
1 mL whole blood and 0.75 mL serum or plasma. (Note: This volume does not allow for repeat testing.)
Container
Lavender-top (EDTA) tube or green-top (lithium heparin) tube or gray-top (sodium fluoride) tube or tan-top (K2 EDTA) tube and gel-barrier tube or red-top tube or EDTA plasma
Collection Instructions
Serum or plasma must be separated from cells within 45 minutes of venipuncture. Send serum or plasma in a plastic transport tube.
Stability Requirements
Whole blood Temperature | Period |
|---|---|
Room temperature | 14 days |
Refrigerated | 14 days |
Frozen | 14 days |
Freeze/thaw cycles | Stable x3 |
Serum or plasma Temperature | Period |
|---|---|
Room temperature | 7 days |
Refrigerated | 14 days |
Frozen | 14 days |
Freeze/thaw cycles | Stable x6 |
Reference Range
GlycoMark®:
• <18 years: Not established
• Adult male: 10.7−32.0 μg/mL
• Adult female: 6.8−29.3 μg/mL
• Glycemic control goal for diabetic patients: >10
Hb A1c (percent):
• Normal: <5.7%
• Increased risk for diabetes: 5.7% to 6.4%
• Ongoing hyperglycemia: >6.4%
Storage Instructions
Refrigerate
Footnotes
LOINC® Map
| Order Code | Order Code Name | Order Loinc | Result Code | Result Code Name | UofM | Result LOINC |
|---|---|---|---|---|---|---|
| 502226 | Hb A1c+GlycoMark(R)(1,5 AG) | 502359 | Hb A1c Diabetic Assessment | %Hb | 4548-4 | |
| 502226 | Hb A1c+GlycoMark(R)(1,5 AG) | 500117 | GlycoMark(R)(1,5 AG) | ug/mL | 53835-5 | |
| Order Code | 502226 | |||||
| Order Code Name | Hb A1c+GlycoMark(R)(1,5 AG) | |||||
| Order Loinc | ||||||
| Result Code | 502359 | |||||
| Result Code Name | Hb A1c Diabetic Assessment | |||||
| UofM | %Hb | |||||
| Result LOINC | 4548-4 | |||||
| Order Code | 502226 | |||||
| Order Code Name | Hb A1c+GlycoMark(R)(1,5 AG) | |||||
| Order Loinc | ||||||
| Result Code | 500117 | |||||
| Result Code Name | GlycoMark(R)(1,5 AG) | |||||
| UofM | ug/mL | |||||
| Result LOINC | 53835-5 |