Clinical UM Guideline

Glycated hemoglobin, (also referred to as glycohemoglobin, glycosylated hemoglobin, HbA1, GHb, or A1C), is a term used to describe a series of stable minor hemoglobin components formed from a combination of hemoglobin and glucose. It is used primarily to identify the plasma glucose concentration over time. This document addresses outpatient HbA_1c and glycated serum proteins (GSPs) testing, both of which have been used in the monitoring of glycemic control in the management of diabetes mellitus (DM).

For information regarding other methods to assess glycemic control for individuals with DM, see:

• CG-DME-42 Continuous Glucose Monitoring Devices
• CG-DME-50 Automated Insulin Delivery Systems
• CG-DME-51 External Insulin Pumps
• CG-LAB-30 Outpatient Laboratory-based Blood Glucose Testing

Medically Necessary:

Glycated serum protein testing (for example, hemoglobin (HbA_1c), albumin, or fructosamine) testing is considered medically necessary for any of the following indications (A-F):

1. The individual is between the ages of 35 and 71 and has overweight or obesity*; or
2. The individual is of any age and is from a population with disproportionately high prevalence of diabetes mellitus**; or
3. Hyperglycemia has been found on other testing; or
4. To test individuals who are pregnant and considered to be at high risk for type 2 diabetes mellitus; or
5. Prior testing at least 3 months previously showed results near diabetes mellitus diagnostic thresholds; or
6. To evaluate glycemic status for individuals with established diabetes mellitus, prediabetes, or a history of gestational diabetes when done no more often than the following test frequencies:
   1. Up to once yearly for individuals with prediabetes; or
   2. Up to two times per year for individuals with diabetes mellitus who are meeting treatment goals; or 
   3. As needed to assess individuals with diabetes mellitus when the following criteria are met (a or b):
      1. Not meeting treatment goals; or
      2. Therapy has recently changed;
         or
   4. Within the first year postpartum and then up to once yearly for individuals who have had gestational diabetes.

Notes:
See the Discussion section below for more information about:
*ADA, ACOG, and USPSTF recommendations about individuals who have overweight or obesity.
**Populations at increased risk to develop diabetes mellitus.

Not Medically Necessary:

Glycated hemoglobin (HbA_1c) testing and glycated serum protein (for example, albumin or fructosamine) testing is considered not medically necessary when the criteria above are not met and for all other indications.

The following codes for treatments and procedures applicable to this guideline are included below for informational purposes. Inclusion or exclusion of a procedure, diagnosis or device code(s) does not constitute or imply member coverage or provider reimbursement policy. Please refer to the member's contract benefits in effect at the time of service to determine coverage or non-coverage of these services as it applies to an individual member.

When services are Medically Necessary:

When services are Not Medically Necessary:
For the procedure codes listed above for all other indications.

Diabetes mellitus (DM) is a disease in which an absolute or relative deficiency of insulin secretion leads to elevated levels of glucose in the blood (hyperglycemia). DM has the potential to cause severe and sometimes fatal acute or chronic medical complications. Optimal DM treatment is often able to prevent or delay development of these complications. The onset of DM is often slow, with a period of abnormal carbohydrate metabolism known as prediabetes often preceding the development of DM. Treatment of prediabetes may prevent or delay the development of DM.

Proactive management of DM requires regular determinations of blood glucose levels. Measuring levels of glycated hemoglobin or other proteins in the blood can indicate the prevailing blood glucose levels over long periods of time. High levels of blood glucose lead to irreversible attachment of a glucose molecule to the N-terminus of protein molecules. The glycated hemoglobin (HbA_1c) test has been shown to predict the risk for development of many of the chronic complications in DM and is the most used indicator of long-term glycemic control. HbA_1c testing can also be used to screen for or to diagnose prediabetes and DM. Alternative names for HbA_1c include glycated hemoglobin, glycosylated hemoglobin, HbA1, A1c or GHb.

HbA_1c levels might not be an accurate measure of long-term glycemic control for individuals with aberrant hemoglobins such as those with sickle cell disease. The HbA_1c level may be artifactually elevated in individuals with vitamin B12 or folate deficiency, for whom red blood cell (RBC) turnover may be reduced. Conversely, those with rapid RBC turnover, as in thalassemia, chronic hemolysis, or recently treated anemia, may have lower than expected HbA_1c levels. Alternatives to HbA_1c measurement for these individuals include frequent fingerstick glucose measurements, continuous glucose monitoring, or measurement of glycated proteins other than hemoglobin. The non-hemoglobin proteins most used for assessment of glycemic control are glycated fructosamine and glycated albumin. Both of these proteins can be affected by conditions that affect serum protein levels, such as protein-losing enteropathy or the nephrotic syndrome. Albumin and other proteins are eliminated from serum at a faster rate compared to hemoglobin. While HbA_1c is considered to reflect glycemic control over the previous 120 days, other glycated proteins may only reflect the average glucose levels for the previous few weeks. More frequent testing may be needed when these tests are used to assess glycemic control.

An RBC has an average life span of 120 days. Since the HbA_1c test measures hemoglobin within RBCs, the HbA_1c level reflects the average plasma glucose levels over the previous 120 days. Diagnostic and therapeutic targets for HbA_1c testing are commonly reported in the US as the percent of hemoglobin that has been glycated in a sample. HbA_1c testing may not be reliable for individuals with hemoglobin variants, (such as sickle cell anemia, sickle cell trait, or thalassemia) or for those with shortened RBC lifespans, (such as those with hemolytic anemia). An organization named NGSP (originally the National Glycohemoglobin Standardization Program) certifies HbA_1c assays and has information about reliable HbA_1c testing that may be available for individuals with hemoglobin variants. Marked discrepancies between measured A1C and plasma glucose levels should prompt consideration that the HbA_1c assay may not be reliable for that individual. An updated list of HbA_1c assays with information about interferences is available at: NGSP: HbA1c Assay Interferences. Other measures of glycemic control, such as self-monitored blood glucose or continuous glucose monitoring, may be appropriate when HbA_1c testing is not thought to be reliable for an individual.

According to the Centers for Disease Control and Prevention (CDC) 2023 National Diabetes Statistics Report, an estimated 19% of all US adults have DM and 38% meet criteria for prediabetes. The prevalence of prediabetes and DM are higher in older adults. Of persons with DM, 21.4% were not aware of or did not report having DM, and only 19% of persons with prediabetes reported being told by a health professional that they had this condition. Estimates of the risk of progression from prediabetes to DM vary widely, perhaps because of variation in the definition of prediabetes or the heterogeneity of prediabetes. The U.S. Preventive Services Task Force (USPSTF) reports that the risk of developing DM increases with increasing HbA_1c level and with increasing body mass index (BMI).

It is especially important to detect and tightly control DM during pregnancy. Suboptimal glycemic control has been well established as a cause for numerous poor health outcomes, including spontaneous abortion, fetal anomalies, preeclampsia, fetal demise, macrosomia, neonatal hypoglycemia, hyperbilirubinemia, and neonatal respiratory distress syndrome. Diabetes in pregnancy also increases risks for chronic illnesses in the offspring’s later life, including obesity, type 2 DM, and hypertension (ADA, 2024).

Populations at Increased Risk to Develop Diabetes Mellitus.

The development of diabetes is influenced by multiple factors (ADA, 2024). Among these factors, being overweight or having obesity are the strongest risk factors for developing prediabetes and type 2 DM in adults. Obesity has been shown to play a major role in the development of diabetes, with one study finding a 100-fold increase in risk for individuals with a BMI >35 kg/m² (36). This risk increases with age (Biggs, 2010). Other significant factors include smoking, with active smokers having an average 1.5-fold increased risk of developing diabetes. There is a direct correlation between the frequency of smoking and risk, with more frequent smokers having increased risk (Willi, 2007). Family history is also a significant risk factor. Having a first degree relative with diabetes is associated with a two to three-fold increased risk of developing diabetes. Individuals with both maternal and paternal family history of diabetes have a 5-to-6-fold increase in their risk of developing diabetes. (InterAct Consortium, 2015; Meigs, 2000). Ethnicity may also significantly increase risks for the development of diabetes. Individuals of Asian, Hispanic, and Black heritage have an almost 2-fold increase in risk. (Menke, 2015; Shai, 2006). Many medications impair glucose tolerance and place individuals at increased risk for developing complications including overweight, obesity, diabetes, and diabetic ketoacidosis. These medications include statins, antipsychotics, corticosteroids, and others (ADA, 2024; Brooks, 2009; Bobes, 2003; Cooper, 2016; Elena, 2018; Holt, 2019; Leslie, 2004; Sattar, 2023). Periodic blood glucose monitoring is indicated for these individuals to detect and manage their risks for diabetes and its complications.

Measurement and monitoring of HbA1c in populations at increased risk of developing diabetes mellitus is considered a key metric in quality healthcare. The National Committee for Quality Assurance (NCQA), an organization responsible for the accreditation of most U.S. health plans, includes HbA1c measurement as a key quality indicator in the Healthcare Effectiveness Data and Information Set (HEDIS) measures (NCQA, 2024). The HEDIS measures specifically evaluate the use of HbA1c measurement in individuals with diabetes and for people with schizophrenia or bipolar disorder who are treated with antipsychotic medications.

Screening for Prediabetes and Type 2 DM

Screening asymptomatic adults for prediabetes and type 2 DM may allow earlier detection, diagnosis, and treatment, with the goal of improving health outcomes.

The USPSTF is a panel of experts appointed by the Agency for Healthcare Research and Quality (AHRQ) to evaluate evidence and produce recommendations for preventive health services. In 2021, USPSTF produced an update to their evaluation and recommendations for screening for prediabetes and type 2 DM. Their recommended screening tests for these purposes include measurement of fasting plasma glucose or HbA_1c level or an oral glucose tolerance test (USPSTF, 2021[a]).

The 2021 USPSTF document made only one graded recommendation for screening for prediabetes and type 2 DM:

• The USPSTF recommends screening for prediabetes and type 2 DM in adults aged 35 to 70 years who have overweight or obesity. Grade B (USPSTF, 2021[a])

This recommendation is supported by evidence cited in the published article. Grade B recommendations indicate that the USPSTF has found at least fair evidence that the service improves important health outcomes, concludes that benefits outweigh harms, and that the USPSTF recommends that clinicians provide the service to eligible individuals. (USPSTF Grade Definitions)

USPSTF also made an ungraded recommendation concerning the optimal screening interval for adults. Although they note that the evidence is uncertain, they cite cohort and modeling studies that suggest screening every 3 years may be a reasonable approach for adults with normal blood glucose levels. Screening should include an assessment of risk including height and weight measurements to determine whether the individual has overweight or obesity. They define overweight and obesity as a BMI ≥ 25 and ≥ 30, respectively.

Another ungraded recommendation in the 2021 USPSTF document is to screen individuals who have overweight or obesity and are younger than 35 if they are from a population with a disproportionately high prevalence of DM. They define these populations as American Indian, Alaska Native, Black, Hispanic, Latino, Native Hawaiian, and Pacific Islanders. Noting studies showing that a difference in body fat composition in some persons of Asian descent may result in underestimations of risk, based on BMI thresholds used to define overweight in the US, they recommend that a BMI of 23 or greater may be an appropriate cutoff point for Asian Americans.

The ADA 2024 Standards of Medical Care in Diabetes provide a grade B recommendation that screening of asymptomatic adults for prediabetes and DM should be done with an informal assessment of risk factors or with an assessment questionnaire provided in their document. An ADA grade B recommendation indicates that it is supported by evidence from well-conducted cohort studies.

The ADA makes a stronger (grade A) recommendation for this interview-based screening of children with an identified DM risk factor and with overweight or obesity (BMI ≥ 85^th percentile or ≥ 95^th percentile, respectively). Screening of children should begin after the onset of puberty or at age 10, whichever occurs sooner. The identified risk factors may include:

• Maternal history of DM or gestational DM during the child’s gestation;
• Family history of type 2 DM in first- or second-degree relative;
• High risk race/ethnicity (African American, Asian American, Latino, Native American, Pacific Islander);
• Signs of insulin resistance or conditions associated with insulin resistance (acanthosis nigricans, hypertension, dyslipidemia, polycystic ovary syndrome, or small-for-gestational-age birth weight).

An ADA grade A recommendation indicates that it is supported by clear evidence from well-conducted, generalizable randomized controlled trials that are adequately powered.

The ADA  also recommends blood tests for adults who have overweight or obesity (BMI ≥ 25 kg/m2 or ≥ 23 kg/m2 in Asian Americans) and who have one or more of the following risk factors:

• 35 years of age or older;
• First-degree relative with DM;
• High-risk race/ethnicity (African American, Asian American, Latino, Native American, Pacific Islander);
• History of CVD;
• Hypertension (≥ 130/80 mm Hg or on therapy for hypertension);
• HDL cholesterol level < 35 mg/dL (0.90 mmol/L) and/or a triglyceride level > 250 mg/dL (2.8 mmol/L);
• Individuals with polycystic ovary syndrome;
• Physical inactivity;
• Other clinical conditions associated with insulin resistance (e.g., severe obesity, acanthosis nigricans);
• HIV infection.

The ADA states that testing can be done by fasting plasma glucose, 2-hour glucose tolerance testing, or with an HbA_1c level. (Evidence grade B; ADA, 2023)

In addition to the risk factors identified above by the ADA, the American College of Obstetrics and Gynecology (ACOG) identifies the following risk factors as indications to perform a screening test for individuals with obesity or overweight at their first prenatal visit (ACOG, 2018):

• Individuals with polycystic ovarian syndrome;
• Individuals with previous gestational diabetes (GDM);
• Individuals who have given birth to an infant weighing 4000g (about 9 pounds) or more.

ACOG states that the best screening test for type-2 DM or early GDM has not been established. They refer to ADA’s statement that HbA_1c can be used for early pregnancy type-2 DM screening, but that HbA_1c may not be suitable for use alone in this setting because it is less sensitive than glucose tolerance testing. (ACOG, 2018)

ACOG recommends that “All pregnant women should be screened for GDM with a laboratory-based screening test(s) using blood glucose levels.” They concur with the ADA that GDM screening should be done at 24-28 weeks. (ACOG, 2018)

USPSTF provided updated guidance on screening for GDM in 2021 (USPSTF, 2021[b]). This document makes a grade B recommendation to screen asymptomatic pregnant persons at or after 24 weeks of gestation. A separate grade I (insufficient information) recommendation stated that “The current evidence is insufficient to assess the balance of benefits and harms of screening for gestational diabetes in asymptomatic pregnant persons before 24 weeks of gestation.” (USPSTF, 2021)

The ADA (2024) recommends repeat testing at least every 3 years for individuals who have normal screening test results and for individuals who have had GDM. Individuals who have prediabetes (A1C ≥ 5.7% [39 mmol/mol], impaired glucose tolerance, or impaired fasting glucose) should be tested yearly. They recommend testing more frequently if initial results are near thresholds or if the individual’s risk status changes. The testing frequency recommendation is given a grade of C, indicating that it is supported by poorly controlled or uncontrolled studies.

The ADA recommends that all individuals who are pregnant or are planning to become pregnant receive interview-based screening with testing done if risk factors are identified (grade B recommendation; ADA, 20243). They also make a Grade E recommendation to consider testing all pregnant individuals at their first prenatal visit. An ADA evidence grade of E indicates that it is based on expert consensus or clinical experience. They emphasize the importance of screening individuals in populations at high risk for DM as noted above. Also, as noted above, testing in follow-up to risk screening can be done by fasting plasma glucose, 2-hour glucose tolerance testing, or with an HbA_1c level (Evidence grade B). Individuals whose early pregnancy test shows impaired glucose metabolism should be monitored as noted in the section below on monitoring glycemic control.

When the initial screen and test (if done) are negative, individuals who are pregnant should universally receive rescreening between 24- and 28-weeks’ gestation with an oral glucose tolerance test, or with a glucose loading test followed by an oral glucose tolerance test. The ADA notes that an HbA_1c level done at 15 weeks gestation or later is not a reliable indicator of gestational DM or of preexisting DM.

The American Academy of Child and Adolescent Psychiatry (AACAP) published a practice parameter for the use of atypical antipsychotic medications (referred to as atypical antipsychotic agents [AAA]) in children and adolescents in 2011. That document stated the following:

Recommendation 12. Careful attention should be given to the increased risk of developing diabetes with the use of AAA, and blood glucose levels and other parameters should be obtained at baseline and monitored at regular intervals [CS].

Adult studies have found an association between the development of diabetes/abnormal glucose regulation and the use of AAAs. There is also evidence to suggest that the development of diabetes is not only directly related to weight gain. Therefore, careful monitoring for diabetes, through close attention to the clinical signs and symptoms of diabetes, and regular monitoring of blood glucose levels and, as needed, hemoglobin A1C is warranted.

The AACAP also published their practice parameter for the assessment and treatment of children and adolescents with schizophrenia in 2013, which cite and support the ADA guidelines (McCellan, 2013).

Diagnosis of Prediabetes and DM

A DM diagnosis can be confirmed in the presence of classic symptoms and a random plasma glucose level ≥ 200 mg/dL (ADA, 2023 diagnosis standard). Classic DM symptoms include polyuria, polydipsia, thirst, and weight loss. The diagnosis should be considered in the presence of less pronounced symptoms when there is hyperglycemia. In this circumstance, the ADA recommends that the serologic confirmation should be made with two tests. These two tests can be from the same or from different samples and can be of the same or different test type. Test types used in diagnosing DM include the HbA_1c level, fasting plasma glucose, or a 2-hour glucose tolerance test. A random plasma glucose test should only be considered confirmatory in the presence of classic symptoms.

The ADA (2024) recommends the following diagnostic test findings criteria for screening and diagnosis of DM or prediabetes:

*For all three tests, risk is continuous, extending below the lower limit of the range and becoming disproportionately greater at the higher end of the range.
†In the absence of unequivocal hyperglycemia, diagnosis requires two abnormal test results from the same sample or in two separate samples.
‡Only diagnostic in a patient with classic symptoms of hyperglycemia or hyperglycemic crisis.

The ADA (2024) recommends close follow-up and repeat testing in 3–6 months when the initial test result is near a diagnostic threshold.

Monitoring Glycemic Control

The ADA recommends that nonpregnant adults with established DM should maintain an HbA_1c level less than 7% to reduce long-term microvascular and neuropathic complications. Less stringent HbA_1c goals may be appropriate for individuals with a history of severe hypoglycemia, limited life expectancy, advanced microvascular or macrovascular complications, extensive comorbid conditions, or long-standing DM in whom the goal is difficult to achieve, despite DM self-management education, appropriate glucose monitoring, and effective doses of multiple glucose-lowering agents including insulin (ADA, 2024).

The ADA (, 2024) provides recommendations for monitoring glycemic control in individuals with DM. Options for this monitoring include measurement of HbA_1c, self-monitored blood glucose monitoring, or continuous glucose monitoring (CGM). They point out that the clinical trials demonstrating the benefits of improved glycemic control used HbA_1c as the measure of that control.

The ADA (2024) standards include the following recommendations for repeat measurements of HbA_1c in individuals with confirmed DM:

6.1 Assess glycemic status by A1C and/or appropriate continuous glucose monitoring (CGM) metrics at least two times a year. Assess more frequently (e.g., every 3 months) for individuals not meeting treatment goals, with frequent or severe hypoglycemia or hyperglycemia, changing health status, or growth and development in youth.. (Evidence grade E)

6.2 Assess glycemic status at least quarterly and as needed in patients whose therapy has recently changed and/or who are not meeting glycemic goals. (Evidence grade E)

The ADA (2024) notes several issues that can affect the reliability of HbA_1c testing in pregnancy. Pregnancy is associated with faster RBC turnover. This can artifactually lower the HbA_1c level. As a measure of glycemic control over long periods of time, HbA_1c measurement does not detect the postprandial hyperglycemia that is thought to cause macrosomia. For these reasons, the ADA recommends that self-monitored blood glucose should be the primary indicator of glycemic control in pregnancy. HbA_1c levels can be used as a secondary measure of glycemic control. The target HbA_1c level is 6.0% in pregnancy if that level can be maintained without episodes of hypoglycemia. Both ADA and ACOG recommend testing individuals who have had gestational diabetes within the first year postpartum and then up to once yearly thereafter (ADA, 2024; ACOG, 2018).

Acanthosis nigricans: A skin pigmentation problem characterized by dark, velvety, and thick patches of skin usually formed in the skin folds and creases.
Diabetes can be classified into the following general categories:

• Diabetic ketoacidosis: A complication of diabetes that results from increased levels of a chemical called ketones in the blood. It causes excessive thirst, frequent urination, fatigue, and vomiting. Urgent medical attention is usually recommended.
• Polycystic ovarian syndrome (also known as PCOS):  The most common endocrine disorder in women of reproductive age. The syndrome is named after the characteristic cysts which may form on the ovaries. Causes are believed to be genetic or environmental. Treatment involves exercise and weight loss.
• Type 1 diabetes: Diabetes that is due to autoimmune β-cell destruction, usually leading to absolute insulin deficiency, including latent autoimmune diabetes of adulthood.
• Type 2 diabetes: Diabetes that is due to a progressive loss of adequate β-cell insulin secretion frequently in the background of insulin resistance.
• Specific types of diabetes due to other causes: Includes monogenic diabetes syndromes (such as neonatal diabetes and maturity-onset diabetes of the young), diseases of the exocrine pancreas (such as cystic fibrosis and pancreatitis), and drug- or chemical-induced diabetes, (such as with glucocorticoid use, in the treatment of HIV/AIDS, or after organ transplantation).
• Gestational diabetes mellitus: Diabetes diagnosed in the second or third trimester of pregnancy that was not clearly overt diabetes prior to gestation (ADA, 2023).

Fructosamine or glycated protein: Refers to glycosylated protein present in a serum or plasma sample. Glycated protein refers to measurement of the component of the specific protein that is glycated usually by colorimetric method or affinity chromatography.

Glycated hemoglobin (HbA_1c [also referred to as glycohemoglobin, glycosylated hemoglobin, HbA_1c, HbA1, or A1C]): HbA1c, also called A1C, is a measure of the amount of glucose attached to hemoglobin (Hb) in red blood cells. The higher the glucose levels over the previous 2-3 months, the higher the A1C. The A1C test is used to monitor the glucose levels of patients who have been diagnosed with diabetes. This laboratory test of whole blood assesses glycemic control over a period of 4-8 weeks and appears to be the more appropriate test for monitoring diabetic individuals who are capable of maintaining long-term, stable glycemic control. Glycated hemoglobin (equivalent to hemoglobin A1) refers to the total glycosylated HGb present in erythrocytes, usually determined by affinity or ion-exchange chromatographic methodology. HgbA1c refers to the major component of HGb A1, usually determined by ion-exchange affinity chromatography, immunoassay or agar gel electrophoresis. Measurement of HbA1c may be performed every 3 months to determine whether an individual’s average metabolic control has been maintained within the target range. For more comprehensive information regarding HbA1c assay interferences, see https://ngsp.org/interf.asp. (NGSP, updated June, 2022).

Glycated serum protein (GSP): This laboratory test of total serum or plasma levels assesses the individual’s glycemic control over a period of 1-2 weeks. It is generally considered reasonable to monitor GSP levels monthly in pregnant diabetics. Low laboratory test results for HbA1c or GSP may indicate significant, persistent hypoglycemia, in nesidioblastosis or insulinoma, conditions which are accompanied by inappropriate hyperinsulinemia. A below normal test value is helpful in establishing the hypoglycemic state in these conditions.

Macrosomia: A condition in which a newborn baby is born much larger than average for their gestational age. At full term, a weight of more than 8 pounds, 13 ounces is considered macrosomia. This condition is commonly caused by medical conditions of the mother during the pregnancy, such as obesity or diabetes. Additional causes are related to genetics or a medical condition in the newborn.

Peer Reviewed Publications:

1. Biggs ML, Mukamal KJ, Luchsinger JA, et al. Association between adiposity in midlife and older age and risk of diabetes in older adults. JAMA. 2010; 303:2504.
2. Bobes J, Rejas J, Garcia-Garcia M, et al.; EIRE Study Group. Weight gain in patients with schizophrenia treated with risperidone, olanzapine, quetiapine or haloperidol: results of the EIRE study. Schizophr Res. 2003; 62(1-2):77-88.
3. Brooks JO 3^rd, Chang HS, Krasnykh O. Metabolic risks in older adults receiving second-generation antipsychotic medication. Curr Psychiatry Rep. 2009; 11(1):33-40.
4. Cooper SJ, Reynolds GP, et al. BAP guidelines on the management of weight gain, metabolic disturbances and cardiovascular risk associated with psychosis and antipsychotic drug treatment. J Psychopharmacol. 2016; 30(8):717-748.
5. de Jong M, Woodward M, Peters SAE. Diabetes, glycated hemoglobin, and the risk of myocardial infarction in women and men: A prospective cohort study of the UK Biobank. Diabetes Care. 2020; 43:2050–2059.
6. Elena C, Chiara M, Angelica B, et al. Hyperglycemia and diabetes induced by glucocorticoids in nondiabetic and diabetic patients: revision of literature and personal considerations. Curr Pharm Biotechnol. 2018; 19(15):1210-1220.
7. Holt RIG. Association between antipsychotic medication use and diabetes. Curr Diab Rep. 2019; 19(10):96.
8. InterAct Consortium, Scott RA, Langenberg C, et al. The link between family history and risk of type 2 diabetes is not explained by anthropometric, lifestyle or genetic risk factors: the EPIC-InterAct study. Diabetologia. 2013; 56:60.
9. Koga M, Murai J, Saito H, Kasayama S. Glycated albumin and glycated hemoglobin Are influenced differently by endogenous insulin secretion in patients with type 2 diabetes. Diabetes Care. 2010; 33:270–272.
10. Leslie DL, Rosenheck RA. Incidence of newly diagnosed diabetes attributable to atypical antipsychotic medications. Am J Psychiatry. 2004; 161(9):1709-1711.Meigs JB, Cupples LA, Wilson PW. Parental transmission of type 2 diabetes: the Framingham Offspring Study. Diabetes. 2000; 49:2201.
11. Menke A, Casagrande S, Geiss L, Cowie CC. Prevalence of and Trends in Diabetes Among Adults in the United States, 1988-2012. JAMA . 2015; 314:1021.
12. Sattar N. Statins and diabetes: What are the connections? Best Pract Res Clin Endocrinol Metab. 2023; 37(3):101749.
13. Shai I, Jiang R, Manson JE, et al. Ethnicity, obesity, and risk of type 2 diabetes in women: a 20-year follow-up study. Diabetes Care. 2006; 29:1585.
14. Willi C, Bodenmann P, Ghali WA, et al. Active smoking and the risk of type 2 diabetes: a systematic review and meta-analysis. JAMA. 2007; 298:2654.

Government Agency, Medical Society, and Other Authoritative Publications:

1. American Academy of Child and Adolescent Psychiatry. Practice parameter for the use of atypical antipsychotic medications in children and adolescent. 2011. Available at: https://www.aacap.org/App_Themes/AACAP/docs/practice_parameters/Atypical_antipsychotic_Medications_Web.pdf. Accessed on May 3, 2024.
2. American College of Obstetrics and Gynecology (ACOG). Practice Bulletin No. 190: Gestational Diabetes. Obstetrics & Gynecology. 2018; 131(2):e49-e64.
3. American Diabetes Association (ADA). Standards of Medical Care in Diabetes. Diabetes Care. 2024; 47(Suppl.1):S1–S321.
4. Centers for Disease Control and Prevention (CDC). 2023 National Diabetes Statistics Report. Last Reviewed: November 29, 2023. Available at: https://www.cdc.gov/diabetes/data/statistics-report/index.html. Accessed on May 3, 2024.
5. Centers for Medicare and Medicaid Services (CMS). National Coverage Determination: Glycated Hemoglobin/Glycated Protein. NCD #190.21. Effective November 25, 2002. Available at: https://www.cms.gov/medicare-coverage-database/view/ncd.aspx?ncdid=100&ncdver=1&bc=0. Accessed on May 3, 2024.
6. Jones LV, Ray A, Moy FM, Buckley BS. Update in techniques of monitoring blood glucose during pregnancy for women with pre-existing diabetes. Cochrane Database Syst Rev. 2019; 5(5):CD009613.
7. McClellan J, Stock S; American Academy of Child and Adolescent Psychiatry (AACAP) Committee on Quality Issues (CQI). Practice parameter for the assessment and treatment of children and adolescents with schizophrenia. J Am Acad Child Adolesc Psychiatry. 2013; 52(9):976-990.
8. National Committee for Quality Assurance (NCQA). Healthcare Effectiveness Data and Information Set (HEDIS). 2024. Available at: https://www.ncqa.org/hedis/. Accessed on May 3, 2024.
9. United States Preventive Services Task Force (USPSTF). Final recommendation statement for prediabetes and type 2 diabetes: Screening. August 24, 2021(a). Available at: https://www.uspreventiveservicestaskforce.org/uspstf/recommendation/screening-for-prediabetes-and-type-2-diabetes#:~:text=Screening%20every%203%20years%20may,with%20normal%20blood%20glucose%20levels Accessed on May 3, 2024.
10. United States Preventive Services Task Force (USPSTF). Screening for Gestational Diabetes. JAMA. August 10, 2021(b); 326(6):531-538.
11. Ziegler AG, Rewers M, Simell O, et al. Seroconversion to multiple islet autoantibodies and risk of progression to diabetes in children. JAMA. 2013; 309:2473–2479.

1. American Diabetes Association. Information about diabetes and A1C. Available at: Understanding A1C | ADA (diabetes.org). Accessed on March 10, 2024.
2. United States Preventive Services Task Force (USPSTF). 2018. Grade definitions. Available at:  https://www.uspreventiveservicestaskforce.org/uspstf/about-uspstf/methods-and-processes/grade-definitions#:~:text=B%20%2D%20Recommended%3A%20The%20USPSTF%20recommends,concludes%20that%20benefits%20outweigh%20harms. Accessed on March 10, 2024.

A1C
Albumin
Hemoglobin, glycated or glycosylated Hgb
Glycohemoglobin
HbA_1c
HbA1
Protein, total serum glycated or glycosylated GSP
Fructosamine.

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