DOT/FAA/AM-01/12

Vicky L. White

Arvind K. Chaturvedi

Dennis V. Canfield

Civil Aerospace Medical Institute

Federal Aviation Administration

Oklahoma City, OK 73125

Mitchell Garber

National Transportation Safety Board

Washington, DC 20594

July 2001

Final Report

This document is available to the public

through the National Technical Information

Service, Springfield, VA 22161.

Association of Postmortem Blood

Hemoglobin A1c Levels With

Diabetic Conditions in Aviation

Accident Pilot Fatalities

Office of Aerospace Medicine

Washington, DC 20591

U.S. Department

of Transportation

Federal Aviation

Administration
NOTICE

This document is disseminated under the sponsorship of

the U.S. Department of Transportation in the interest of

information exchange. The United States Government

assumes no liability for the contents thereof.
i

Technical Report Documentation Page

1. Report No. 2. Government Accession No. 3. Recipient's Catalog No.

DOT/FAA/AM-01/12

4. Title and Subtitle 5. Report Date

Association of Postmortem Blood Hemoglobin A July 2001 1c Levels With Diabetic

Conditions in Aviation Accident Pilot Fatalities 6. Performing Organization Code

7. Author(s) 8. Performing Organization Report No.

White, V.L.1 , Chaturvedi, A.K.1, Canfield, D.V.1, and Garber, M.2

9. Performing Organization Name and Address 10. Work Unit No. (TRAIS)

11. Contract or Grant No.

1

FAA Civil Aerospace Medical Institute

P.O. Box 25082

Oklahoma City, OK 73125

2

National Transportation

Safety Board

Washington, DC 20594

12. Sponsoring Agency name and Address 13. Type of Report and Period Covered

Office of Aerospace Medicine

Federal Aviation Administration

800 Independence Ave., S.W.

Washington, DC 20591 14. Sponsoring Agency Code

15. Supplemental Notes

This work was accomplished under the approved tasks AM-B-00-TOX-202 and AM-B-01-TOX-202

16. Abstract

Purpose. The Federal Aviation Administration's (FAA's) Office of Aerospace Medicine evaluates present and

proposed medical certification standards for pilots. Under this responsibility, the FAA Civil Aerospace Medical

Institute investigates the role of potential medical-or drug-related performance impairment in pilots. In

previous research, abnormal glucose levels in vitreous humor (>125 mg/dL) and urine (>100 mg/dL) have been

linked with diabetic conditions in pilots of fatal aviation accidents. Although these abnormal glucose levels

identify pilots with elevated blood sugar at the time of death, they do not provide information on how well

diabetes was controlled in these pilots. Since post-crash factors (trauma, stress, medical intervention) can

dramatically affect blood glucose levels, a measure of long-term diabetic control was sought for postmortem

specimens. Methods. Blood specimens from volunteers were collected and stored at room temperature for up

to 52 days to mimic a postmortem condition. These specimens were analyzed for hemoglobin A1c

 (HbA1c) at

selected time intervals during the 52-day period. Postmortem blood specimens from 34 aviation accident pilot

fatalities were also analyzed. Some of these pilots had a known history of diabetes. Results. HbA1c

 values in

blood from volunteers did not significantly change for up to 52 days. The HbA1c concentration in postmortem

blood samples from pilots ranged from 3.9-10.5%. Only one pilot with a HbA1c

 over 6.0% did not have a

history of diabetes reported to the FAA. Conclusions. HbA1c

 is stable in whole blood stored at room

temperature for 52 days and appears to be stable in postmortem blood stored up to 84 days. HbA1c above 6.0%

was found to be generally correlated with a known history of diabetes and with the abnormal vitreous humor

and urine glucose levels established previously. Elevated postmortem HbA1c levels may be useful in supporting

determinations of medical impairment/incapacitation in transportation accidents.

17. Key Words 18. Distribution Statement

Forensic Science, Toxicology, Diabetes, Glucose, Urine,

Vitreous Humor, Postmortem Aircraft Accident

Investigation

Document is available to the public through the

National Technical Information Service

Springfield, VA 22161

19. Security Classif. (of this report) 20. Security Classif. (of this page) 21. No. of Pages 22. Price

Unclassified Unclassified 7

Form DOT F 1700.7 (8-72) Reproduction of completed page is authorized

1

ASSOCIATION OF POSTMORTEM BLOOD HEMOGLOBIN A1C LEVELS WITH

DIABETIC CONDITIONS IN AVIATION ACCIDENT PILOT FATALITIES

INTRODUCTION

Research into the use of hemoglobin A1C (HbA1C)

began in the late 1960s and has continued to gain

favor over the years for the diagnosis of diabetes

mellitus (1-12). In fact, the analysis of HbA1C has

become a routine test for the diagnosis of diabetes

and the monitoring of diabetic patients. The strong

correlation found between elevated HbA1C and diabetes (9) has made this analysis a very popular tool in

the diagnosis and treatment of diabetics.

HbA1C is formed through the irreversible reaction

of glucose with hemoglobin at the NH2

-terminus of

one or both beta chains of hemoglobin (4) and is

reported as a percentage of the total hemoglobin

present in the specimen. Normal non-diabetic individuals have HbA1C levels between 3 – 6 % (11). The

life expectancy of the red blood cell is 2 - 3 months.

Therefore, HbA1C will provide information on the

patient’s long-term success in treating their diabetic

condition over the past 2 – 3 months.

A previous study has shown a correlation between

diabetic pilots and elevated postmortem vitreous

humor and urine glucose levels (2). This information

has helped accident investigators assess the medical

condition of the pilot at the time of the accident and

allowed the Office of Aviation Medicine (OAM) to

closely monitor medical certification standards concerning diabetic pilots.

Vitreous humor glucose levels can be influenced

by several non-diabetic factors such as stress and

medications. Therefore, it would be useful to know

the HbA1C level of the pilot to confirm the diagnosis

of diabetes and help assess the pilot’s prior control of

the diabetic condition.

The analysis of blood collected from aviation

accidents is complicated by the frequent delay of

several weeks in receiving specimens. Autopsies are

often delayed by difficulties in recovering bodies

from remote accident sites, specimen collection, and

sending samples to the laboratory. This delay in

analysis requires that HbA1C levels be stable in postmortem blood for extended periods of time. Earlier

studies (4 – 8) have reported HbA1C stability in

postmortem blood collected and tested shortly after

death. This study intends to examine the stability of

HbA1C in blood stored over an extended period of time.

MATERIALS AND METHODS

Materials

All reagents and blood specimens were allowed to

reach room temperature prior to analysis. A 1 uL

sample of thoroughly mixed whole blood specimen

was placed into the glass capillary provided in the

DCA 2000 Hemoglobin A1c Reagent Kit and analyzed according to the manufacturer’s operating instructions with a DCA 2000+ Analyzer and DCA

2000 Hemoglobin A1c Reagent Kit (Bayer Corporation, Elkhart, IN).

Clinical Specimens

A blood sample was drawn from a known diabetic,

and another sample from a non-diabetic individual.

Blood was collected into tubes containing the anticoagulant EDTA and stored at room temperature. These

specimens were analyzed over a period of 52 days.

The collection time was noted, and analyses were

performed at periodic intervals. This was done to

demonstrate the stability of HbA1C in blood stored at

room temperature for an extended period of time.

Necropsy Specimens

Blood was collected by local pathologists, located

near the accident site, in 10 mL gray top tubes

containing 20 mg of potassium oxalate and 100 mg

of sodium fluoride (Tri-Tech Inc., Southport, NC)

from 34 pilots who had died in aviation accidents.

Postmortem blood specimens from aviation pilots

were aliquoted into tubes and frozen for analysis at a

later date. HbA1C was determined in postmortem

blood samples, which were 7 to 84 days old.
2

RESULTS

Clinical Specimens

A blood specimen taken from a known diabetic

subject had an average HbA1C of 10.2 %, when tested

over a period of 52 days with a 0.5 % standard

deviation (n=12). A blood specimen taken from a

non-diabetic subject had an average hemoglobin A1c

of 4.9 % with standard deviation of 0.1 % (n=12) for

the same period of time (Figure 1).

Necropsy Specimens

HbA1C levels above 6% were found in 8 of the 34

postmortem cases analyzed (Table 1). A medical

history of diabetes mellitus was found in 6 of the 8

cases with elevated HbA1C. One case with a 10.5%

HbA1C had a medical history of glycosuria. Another

pilot had a 6.7% HbA1C level and no reported medical

history of diabetes. Most of the elevated HbA1C

specimens analyzed were associated with elevated

glucose levels in vitreous and/or urine.

DISCUSSION AND CONCLUSION

HbA1C levels above 6% are generally correlated

with a known history of diabetes. It may also be

considered diagnostic of diabetes mellitus in postmortem blood. Elevated postmortem HbA1C levels, in

combination with elevated glucose levels in vitreous

Figure 1. Comparison of Diabetic and Non-diabetic Subject HbA1C Levels.

HbA1C was analyzed for 52 days. The diabetic blood sample had a 407

mg/dL glucose level on the first day of the test, and the non-diabetic blood

sample had a glucose level of 92 mg/dL on the first day of the test.

0

3

6

9

1 2

0 13 26 39 52

Days

HbA1c (%)

N on-diabetic

[4.9 + 0.1]

D iabetic

[10.2 + 0.5]
3

Table 1. HbA1Cand glucose data collected in this study. All glucose data reported in

mg/dL. Interval between death and analysis is reported in days. Medical refers to

medical history of the individual: NO = No medical history for abnormal glucose levels;

PA = Passenger no medical history on file; PM = Pilot no medical history on file; DI =

Diabetic; EM = Emergency medical treatment; GL = Glycosuria or low renal threshold;

SU = surface accident, no medical history on file.

Case Number

Urine

Glucose

Vitreous

Glucose Accident Date Date of Result Interval (days) Medical HbA1C (%)

199800208001 3055 12 05-Jul-98 19-Aug-98 45 GL 10.5

199800290001 8815 256 25-Sep-98 17-Nov-98 53 DI 8.5

199910012001 1221 03-Jun-99 08-Jul-99 35 DI 8.0

199900049001 38 97 22-Mar-99 12-Apr-99 21 DI 7.5

199800186001 189 45 26-Jun-98 18-Aug-98 53 DI 6.6

199800332001 760 119 04-Dec-98 13-Jan-99 40 DI 6.4

199800134001 28 43 26-May-98 18-Aug-98 84 DI 6.1

199900208001 29 20-Aug-99 30-Aug-99 10 DI 5.6

199800301001 11 0 12-Oct-98 18-Nov-98 37 DI 5.0

199900181001 109 07-Aug-99 16-Aug-99 9 DI 4.5

199900037001 65 113 08-Mar-99 19-Mar-99 11 EM 4.7

199800216001 65 147 31-Jul-98 18-Aug-98 18 EM 4.6

199900047001 194 10-Mar-99 12-Apr-99 33 EM 4.6

199800289001 24 10 10-Oct-98 17-Nov-98 38 EM 3.9

199800251001 0 12-Sep-98 25-Sep-98 13 EM 3.9

199800335001 18 105 04-Dec-98 13-Jan-99 40 NO 6.7

199900030001 67 66 20-Feb-99 01-Mar-99 9 NO 5.8

199800328001 12 0 21-Nov-98 13-Jan-99 53 NO 5.4

199800212001 14 0 31-Jul-98 18-Aug-98 18 NO 5.1

199800305001 18 0 02-Nov-98 18-Nov-98 16 NO 5.0

199900053001 0 0 03-Apr-99 12-Apr-99 9 NO 4.9

199800333001 0 0 29-Nov-98 13-Jan-99 45 NO 4.8

199800265001 42 102 26-Sep-98 17-Nov-98 52 NO 4.8

199800229001 87 10 12-Aug-98 01-Sep-98 20 NO 4.8

199800188001 29 66 10-Jul-98 18-Aug-98 39 NO 4.7

199800317001 14 0 12-Nov-98 13-Jan-99 62 NO 4.6

199900017001 13 0 26-Dec-98 05-Feb-99 41 NO 4.5

199900067001 12 0 22-Apr-99 11-May-99 19 NO 4.4

199900040001 15 0 13-Mar-99 12-Apr-99 30 NO 4.3

199800209001 0 0 26-Jul-98 18-Aug-98 23 NO 4.2

199900162001 12 0 17-Jul-99 27-Jul-99 10 NO 4.2

199800217001 17 0 02-Aug-98 18-Aug-98 16 NO 4.2

199900083001 20 0 04-May-99 11-May-99 7 NO 4.0

199900012002 14 13 22-Jan-99 23-Feb-99 32 PA 4.2
4

and/or urine, could be useful in supporting determinations of medical impairment/incapacitation in

transportation accidents.

HbA1C levels are stable in a clinical whole blood

specimen stored at room temperature for 52 days

(Fig. 1) and appear to be stable in necropsy whole

blood stored up to 84 days. This finding is consistent

with early reports on HbA1C in postmortem whole

blood.

The pilot originally diagnosed with glycosuria was

most likely a diabetic, considering the 10.5% HbA1C

found in the pilot’s blood and the 3055 mg/dL of

glucose found in the urine. Research has shown a 3%

increase in HbA1C levels above normal (>8%) “generally indicate that mean plasma glucose concentrations have been well over 2000 mg/L” (200 mg/dL)

during the past 2-3 months (4).

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Clinical Chemistry, 1994. 40/7, 1317-1321

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Glycated hemoglobin: methodologies and

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