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Protocol - Fasting Serum Insulin

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Description:

This protocol provides instructions for drawing, processing and storing blood according to the National Health and Nutrition Examination Survey (NHANES) methods. As there are no standard assays for insulin, the protocol also provides basic guidelines to aid comparability among different studies.

Protocol:

The following is a summary version of the full National Health and Nutrition Examination Survey 2007-2008 protocol.

Exclusion Criteria

Persons will be excluded from this component if they:

• Report that they have hemophilia; • Report that they have received cancer chemotherapy in the last 3 weeks; and • Report that they have not fasted at least 9 hours.

SP = Sample Person.

1. Did you eat or drink anything other than plain water after [Insert time at 9 hours prior to sample collection] last night?

[ ] Yes

[ ] No

[ ] Refused

[ ] Don’t Know

If the answer is "No," then he or she has met the 9-hour fast. If the answer is "Yes," "Don’t know," or "Refused," then the actual fasting time is unknown.

Confirmation Question:

2. Have you had any of the following since {insert time from 1 here}?

Coffee or tea with cream and sugar? [Include milk or non-dairy creamers.]

[ ] Yes If Yes, record time and date _____________

[ ] No

Alcohol, such as beer, wine, or liquor?

[ ] Yes If Yes, record time and date _____________

[ ] No

Gum, breath mints, lozenges, or cough drops, or other cough or cold remedies?

[ ] Yes If Yes, record time and date _____________

[ ] No

Antacids, laxatives, or anti-diarrheals?

[ ] Yes If Yes, record time and date _____________

[ ] No

Dietary supplements such as vitamins and minerals? [Include multivitamins and single nutrient supplements.]

[ ] Yes If Yes, record time and date _____________

[ ] No

3. Do you have hemophilia?

1 [ ] Yes

2 [ ] No

7 [ ] Refused

9 [ ] Don’t Know

If the SP answers "Yes," the SP is excluded from the blood draw. If the SP answers "No" or "Don’t Know," blood is drawn from the SP.

4. Have you received cancer chemotherapy in the past 4 weeks or do you anticipate such therapy in the next 4 weeks?

1 [ ] Yes

2 [ ] No

7 [ ] Refused

9 [ ] Don’t Know

If the SP answers "Yes," the SP is excluded from the blood draw. If the SP answers "No" or "Don’t Know," blood is drawn from the SP.

Venipuncture Procedures

Editor’s Note: Please review chapter 4 of the Laboratory Procedures Manual from the National Health and Nutrition Examination Survey for a full description of Phlebotomy procedures. 2007-2008 NHANES Lab Manual.

Venipuncture should generally be performed using the median cubital, cephalic, or basilic veins in the left arm unless this arm is unsuitable. If the veins in the left arm are unsuitable, look for suitable veins on the right arm. If the veins in the antecubital space on both arms are not suitable, then look for veins in the forearm or dorsal side of the hand on the left arm/hand and then the right arm/hand.

Recording the Results of the Venipuncture Procedure

Immediately after completing the venipuncture, record the results of the blood draw, the reasons for a tube not being drawn according to the protocol, and any comments about the venipuncture.

Blood Processing

Editor’s Note: Please review chapter 8 of the Laboratory Procedures Manual from the National Health and Nutrition Examination Survey 2007-2008 for a full description of Blood Processing procedures: 2007-2008 NHANES Lab Manual.

• Allow the blood to clot by setting aside for 30-45 minutes at room temperature. Do not clot for more than 1 hour.

• Centrifuge the tube at room temperature to separate the serum and aliquot into an appropriate storage tube.

• Determine if the serum is hemolyzed, turbid, lipemic, or icteric. If so, enter a comment to describe the plasma.

Laboratory Assay for Serum Insulin

The Diabetes Working Group (WG) notes that although there is not a standardized assay, there are a number of different kits that are appropriate to measure the concentration of insulin in serum. Once an assay is chosen for a particular study, the WG recommends that no changes in the protocol be made over the course of the study. To aid comparability, the Diabetes WG recommends that the investigator record the make and manufacturer of equipment used and the repeatability and coefficients of variation for the assay.

Reference Ranges:

Concentrations of fasting insulin normally ranges between 3 uU/mL and 17 uU/mL.

Protocol Name from Source:

2007 National Health and Nutrition Examination Survey (NHANES) Laboratory Procedures Manual

Availability:

Publicly available

Personnel and Training Required

Phlebotomist Laboratory capable of performing insulin assay

Equipment Needs

Phlebotomy supplies

Requirements
Requirement CategoryRequired
Major equipment No
Specialized training No
Specialized requirements for biospecimen collection No
Average time of greater than 15 minutes in an unaffected individual No
Mode of Administration

Bioassay

Life Stage:

Child, Adolescent, Adult, Senior

Participants:

Participants 6 years of age and older

Specific Instructions:

Although all three are valuable standalone measures and all should be collected if resources are available, the Diabetes Working Group (WG) recommends that investigators prioritize Insulin first, C-peptide second, and Proinsulin third. This is because results from the Insulin bioassay can be combined with results from Fasting Plasma Glucose bioassay to derive the homeostatic model assessment (HOMA) of insulin resistance and pancreatic beta cell function. The Diabetes WG notes that while it is not the preferred method, the Serum Insulin assay can be performed on individuals who have not met the fasting requirements. The Diabetes WG notes that there are also protocols to collect samples for serum insulin concentrations at 0 minutes, 30 minutes, 60 minutes, 90 minutes, and 120 minutes and that this could be done at the same time as the Oral Glucose Tolerance Test. Such protocols would give extra specificity and information but would increase the burden on both the participant and investigator.

Note from the Diabetes WG: Rather than asking if the subject had anything to eat or drink after 11:30, the WG notes that is acceptable to record the current time and the time when the subject last had anything other than plain water.

Note from the Diabetes WG: The investigator should record the reason a sample person is excluded from the blood draw, whether the subject is fasting, and the number of hours since the last meal.

Note from the Diabetes WG: Blood should be collected in an appropriate 5 mL or 10 mL red-top tube or serum separator tube.

Note from the Diabetes WG: The Diabetes WG recommends that the investigator record whether the blood was drawn and whether the full amount was obtained.

Note from the Diabetes WG: Serum should be stored at -80°C until testing and shipped on dry ice to prevent thawing. If significant hemolysis is present, this can result in an artificially low insulin level due to insulin degradation.

Note from the Expert Review Panel: Plasma or Serum

Collection of blood samples for the measurement of analytes requires a general determination of whether to use serum or plasma for the assay and also a determination of the type of collection tube to be obtained. For example, if serum is to be used, a determination needs to be made as to whether red-top or serum gel separator collection tubes are used. While comparable values are obtained for many analytes from either serum or plasma, there may be situations where differences are more pronounced and serum or plasma specific norms will be needed for references. The protocol presented here uses red-top/serum separator tubes. At times it may be possible to collect both, but other considerations, such as participant burden, may be the deciding factor. It is important to match assay type with sample type. Some automated devices may preclude the use of serum, for example, while others may be optimized for it. Investigators should choose methods of collection that match the methods of analysis. This will best be done by communicating with the laboratory where the proposed assays will be performed. The laboratory will become an important partner with you in assuring that there is compatibility from collection to assays to interpretation and reporting of levels and results.

Selection Rationale

The National Health and Nutrition Examination Survey (NHANES) 2007-2008 protocol was selected as the best, standardized methodology for blood collection, processing, and storage. Serum insulin has been measured in the NHANES since 1988.

Language

English, Spanish

Standards
StandardNameIDSource
Common Data Elements (CDE) Hematology Fasting Serum Insulin Laboratory Procedure Result Value in mU/L 3070721 CDE Browser
Logical Observation Identifiers Names and Codes (LOINC) Fasting serum insulin proto 62805-7 LOINC
Derived Variables

Homeostasis model assessment (HOMA) of insulin resistance and beta cell function

insulin resistance = (glucose (mg/dL) X insulin (μU/mL))/405

percent B-cell function = (20 X insulin (μU/mL))/(glucose (mg/dL)/ - 63)

or

insulin resistance = (glucose (mmol/L) X insulin (μU/mL))/22.5

percent B-cell function = (20 X insulin (mg/dL))/(glucose (mmol/L)/ - 3.5)

Matthews, D. R., Hosker, J. P., Rudenski, A. S., Naylor, B. A., Treacher, D. F., & Turner, R. C. (1985). Homeostasis model assessment: Insulin resistance and b-cell function from fasting plasma glucose and insulin concentrations in man. Diabetologia, 28(7), 412-419.

Process and Review

The Expert Review Panel #1 reviewed the measures in the Anthropometrics, Diabetes, Physical Activity and Physical Fitness, and Nutrition and Dietary Supplements domains.

Guidance from the ERP includes:

• Added recommendations on use of serum or plasma

Back-compatible: no changes to Data Dictionary

Previous version in Toolkit archive (link)

Source

Centers for Disease Control and Prevention (CDC), National Center for Health Statistics (NCHS). (2007). National Health and Nutrition Examination Survey Questionnaire. Laboratory Procedures Manual. Hyattsville, MD: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention.

General References

American Diabetes Association (ADA). (2014). Diagnosis and classification of diabetes mellitus. Diabetes Care, 37(Suppl. 1), S81-S90.

Miles, R. R., Roberts, R. F., Putnam, A. R., & Roberts, W. L. (2004). Comparison of serum and heparinized plasma samples for measurement of chemistry analytes [Letter to the Editor]. Clinical Chemistry, 50(9), 1704-1705.

Protocol ID:

141301

Variables:
Export Variables
Variable NameVariable IDVariable DescriptionVersiondbGaP Mapping
PX141301_Alcohol PX141301020201 Have you had any of the following since {insert time from 1 here}? Alcohol, such as beer, wine, or liquor? 4 N/A
PX141301_Alcohol_Date PX141301020203 If Yes, record date 4 N/A
PX141301_Alcohol_Time PX141301020202 If Yes, record time 4 N/A
PX141301_Antacids PX141301020401 Have you had any of the following since {insert time from 1 here}? Antacids, laxatives, or anti-diarrheals? 4 N/A
PX141301_Antacids_Date PX141301020403 If Yes, record date 4 N/A
PX141301_Antacids_Time PX141301020402 If Yes, record time 4 N/A
PX141301_Assay_Repeatability PX141301110000 Repeatability of the assay 4 N/A
PX141301_Assay_Type PX141301090000 Type of assay performed to determine the concentration of Insulin 4 N/A
PX141301_Blood_Draw_Comments PX141301060300 Record any comments about the blood draw, including any reasons for the tube not being drawn according to the protocol. 4 Variable Mapping
PX141301_Blood_Draw_Done PX141301060100 Was blood drawn? 4 Variable Mapping
PX141301_Blood_Draw_Sample PX141301060200 Was full sample obtained? 4 Variable Mapping
PX141301_Chemotherapy PX141301040000 Have you received cancer chemotherapy in the past four weeks or do you anticipate such therapy in the next four weeks? (exclusion from Phlebotomy) 4 N/A
PX141301_Coefficient_Of_Variation PX141301120000 Coefficient of variation for the assay 4 N/A
PX141301_Coffee_Tea PX141301020100 Have you had any of the following since {insert time from 1 here}? Coffee or tea with cream and sugar? [Include milk or non-dairy creamers.] 4 Variable Mapping
PX141301_Coffee_Tea_Date PX141301020102 If Yes, record Date 4 N/A
PX141301_Coffee_Tea_Time PX141301020101 If Yes, record time 4 N/A
PX141301_Dietary_Supplements PX141301020501 Have you had any of the following since {insert time from 1 here}? Dietary Supplements such as vitamins and minerals? [Include multivitamins and single nutrient supplements.] 4 N/A
PX141301_Dietary_Supplements_Date PX141301020503 If Yes, record date 4 N/A
PX141301_Dietary_Supplements_Time PX141301020502 If Yes, record time 4 N/A
PX141301_Eat_Or_Drink PX141301010000 Did you eat or drink anything other than plain water after 11:30 last night? 4 N/A
PX141301_Equipment_Make_Manufacturer PX141301100000 Make and manufacturer of the equipment used 4 N/A
PX141301_Exclusion_Criteria PX141301050000 Exclusion Criteria 4 N/A
PX141301_Fasting_Or_Casual_Insulin_Concentration PX141301140000 Was the participant fasting? 4 N/A
PX141301_Gum PX141301020301 Have you had any of the following since {insert time from 1 here}? Gum, breath mints, lozenges, or cough drops, or other cough or cold remedies? 4 N/A
PX141301_Gum_Date PX141301020303 If Yes, record date 4 N/A
PX141301_Gum_Time PX141301020302 If Yes, record time 4 N/A
PX141301_Hemophilia PX141301030000 Do you have hemophilia? (exclusion from Phlebotomy) 4 Variable Mapping
PX141301_Insulin_Concentration PX141301130000 Insulin concentration 4 N/A
PX141301_Last_Eat_Or_Drink_Date PX141301010200 When did you last eat or drink anything other than plain? 4 Variable Mapping
PX141301_Last_Eat_Or_Drink_Time PX141301010100 When did you last eat or drink anything other than plain water? 4 Variable Mapping
PX141301_Sample_Comments PX141301080000 Record any comments about the sample during processing. 4 Variable Mapping
Research Domain Information
Measure Name:

Fasting Serum Insulin

Release Date:

October 1, 2015

Definition

A bioassay to measure serum concentration of insulin, a hormone produced by pancreatic beta cells that regulates the body’s ability to metabolize glucose.

Purpose

Concentrations of serum insulin may help distinguish between type 1 and type 2 diabetes. Type 1, or insulin-dependent, diabetes is characterized by autoimmune destruction of the pancreas and eventually leads to absolute insulin deficiency and very low or no circulating insulin. Type 2, or non-insulin-dependent, diabetes is characterized by insulin resistance and subjects initially have much higher circulating insulin concentrations. This may be followed by decreasing insulin levels due to pancreatic beta cell exhaustion (ADA, 2014). Further, fasting serum insulin alone or combined with fasting plasma glucose can be used as a surrogate estimate of insulin resistance and beta-cell function.

Keywords

Diabetes, proinsulin, C-peptide, pancreas, hyperglycemia, homeostatic model assessment, HOMA, insulin resistance, NHANES