AVANTIKA PATHAK AND DR. ADRIANE FUGH-BERMAN

Is HbA1c a rational screening test for diabetes?

Criteria for diagnosing diabetes:

Organization

Proposed HbA1c value to diagnose type 2 diabetes mellitus (acknowledging the allowed variability of 0.5% in results obtained from NGSP verified laboratory tests)

Repeat HbA1c test to confirm diagnosis

Fasting Plasma Glucose (FPG) recommended to confirm diagnosis

ADA (American DiabetesAssociation) HbA1c ≥ 6.5%

Only if no clinical symptoms are present No

WHO (World Health Organization) HbA1c ≥ 6.5%

According to the InternationalExpert Committee:

Only if patient does not have clinical symptoms and an

accompanying glucose level of > 200 mg/dL

No

NIDDK (National Institute of Diabetes and Digestive and

Kidney Diseases)HbA1c ≥ 6.5% Yes No

VA (Department of Veteran Affairs) HbA1c ≥ 6.5%

If HbA1c ≥ 7%, another test should be done on a

separate occasion to confirmthe diagnosis of diabetes.

If HbA1c ≥ 6.5% and <7%, an FPG ≥ 126 mg/dL should

be done to confirm thediagnosis of diabetes.

THE EFFECT OF RACE AND ETHNICITY ON HbA1C VALUES

ØNon-diabetic African-American and Mexican-American children aged 4 to 17 had a higher HbA1c than non-Hispanic Whites (Herman and Cohen 2012).

Ø African-Americans, Hispanics, and Asians with “glucose intolerance, recent-onset type 2 diabetes, and long-standing type 2 diabetes” with or without medication had significantly higher HbA1c levels than Whites (Herman and Cohen 2012) .

Ø Study on variation of HbA1c for a large range of fasting glucose levels in Singaporean citizens of Chinese, Malay, and Indian origin (Venkataraman et al. 2012).

-Fasting glucose below 5.0 mmol/l, Malays and Indians had a lower HbA1c than the Chinese and for a fasting glucose above 5.0 mmol/l both groups’ HbA1c was higher than that of the Chinese.

HEMOGLOBIN VARIANTS AND THE IMPACT OF ANEMIA ON HbA1C VALUES

Ø Overlap of hemoglobin variants and diabetes (Rhea et al. 2012):§ 305,000 to 383,000 of the 13% to 16.3% of non-Hispanic African-American patients diagnosed

with diabetes have the HbS or HbC trait. § 4.7 million of the 9.2% of the Indian population that has diabetes also has the HbS or HbC trait.§ 1 million Thai people have both HbE and diabetes.

Ø El-Agouza et al. 2002 study: Found HbA1c levels decreased from 6.15% ± 0.62 before beginning treatment to 5.25% ± 0.45 after 20 weeks of treatment with iron.

Ø Hardikar et al. study: Found that Indian youth with iron, vitamin B12, and folate deficiencies had a 21% higher likelihood of being diagnosed with diabetes or prediabetes based when using HbA1c results versus oral glucose tolerance test results (English et al. 2015).

Majority of studies depicted an iron deficiency dependent increase in HbA1c of non-diabetic individuals with and without anemia (English et al. 2015).

CURRENT GLYCEMIC TARGETS FOR PATIENTS WITH TYPE 2 DIABETES:

According to the VA:

Current Evidence:

v Action in Diabetes and Vascular Disease study: No significant improvement in major cardiovascular events or mortality in participants who had reached the study’s established target of HbA1c levels less than 6.5% (Hare et al. 2012).

v A target of HbA1c levels below 6.0% resulted in an increase in mortality in the experimental group (Hare et al. 2012).

Patient-Specific Factors:

v Comorbidities and and their respective medication regimens (VA Guidelines)v Variation in HbA1c values based on ethnicity, hemoglobin variants, and anemia v Social determinants of health (VA Guidelines)

RECOMMENDATION à Use flexible guidelines and design individual risk-benefit analysis based on current evidence and patient-specific factors to determine glycemic targets for patients with type 2 diabetes.