Diabetes Mellitus

Diagnosis

Indications for Testing

  • Known risk factors for type 2 diabetes mellitus (DM)
    • Obesity (BMI >25 kg/m2) – consider testing to detect pre-DM and type 2 DM in asymptomatic people
    • Family history of type 2 DM in first- or second-degree relative
    • Race/ethnicity – Native American, African American, Latino, Asian American, Pacific Islander
    • Signs of insulin resistance or conditions associated with insulin resistance (eg, acanthosis nigricans, hypertension, dyslipidemia, PCOS, low birthweight)
    • Maternal history of DM or gestational diabetes mellitus (GDM) during gestation

Criteria for Diagnosis

  • Criteria for diagnosis of DM

    Criteria for Diagnosis of DM (ADA, 2014)*

    Test

    Result

    Comment

    HbA1c

    ≥6.5%

    If patient has discordant results on two tests (eg, FPG versus HbA1c), then the higher of the two values is used

    FPG

    ≥126 mg/dL (7.0 mmol/L)

    Fasting is defined as no caloric intake for at least 8 hours

    2-hr PG during OGTT

    ≥200 mg/dL (11.1 mmol/L)

    Test should be performed as described by WHO, using a glucose load containing the equivalent of 75-g of anhydrous glucose dissolved in water

    Random PG

    ≥200 mg/dL (11.1 mmol/L)

    In patient with classic symptoms of hyperglycemia or hyperglycemic crisis

    Abbreviations: HbA1c = glycosylated hemoglobin, type A1c; FPG = fasting plasma glucose; PG = plasma glucose; OGTT = oral glucose tolerance test

    *Diagnosis must meet one of the following

    Categories of increased risk for diabetes (prediabetes or impaired glucose tolerance)
    Categories of Increased Risk for Diabetes (Pre-DM)
    TestResult

    FPG

    100-125 mg/dL (5.6-6.9 mmol/L)

    2-hr PG during 75-g OGTT

    140-199 mg/dL (7.8-11.0 mmol/L)

    HbA1c

    5.7-6.4%

    Abbreviations: HbA1c = glycosylated hemoglobin, type A1c; FPG = fasting plasma glucose; PG = plasma glucose; OGTT = oral glucose tolerance test

Laboratory Testing

  • Initial testing – FPG, 2-hr OGTT, random PG, or HbA1c are the preferred tests to diagnose diabetes in nonpregnant adults (see Criteria for Diagnosis)
  • Insulin antibodies  – not recommended for routine evaluation or management of DM (ADA, 2014)
    • Type 1 DM  – results typically have antibodies present and low C-peptide levels
      • Presence of multiple insulin antibodies is highly suggestive of type 1 DM
    • Absence of antibodies or normal C-peptide levels does not rule out type 1, but likelihood of type 1 DM is low in children
      • C-peptide testing is not recommended to diagnose DM
    • Antibody tests

      Antibody Test

      Indications

      Insulinoma antigen 2 (IA-2)

      Distinguish type 1 from type 2 DM in in children to institute insulin therapy at the time of diagnosis

      Identify subset of adults with type 2 DM phenotype who progress rapidly to insulin dependency

      Recommended in combination for initial screening of suspected cases of type 1 DM

      Screen nondiabetic family members who wish to donate a kidney or partial pancreas

      Screen women with GDM to identify those at high risk of progression to type 1 DM

      Glutamic acid decarboxylase (GAD)

      Same as IA-2 indications

      Insulin autoantibodies  (IAA)

      Distinguish type 1 from type 2 DM in in children to institute insulin therapy at the time of diagnosis

      Identify subset of adults with type 2 DM phenotype who progress rapidly to insulin dependency

      Screen nondiabetic family members who wish to donate a kidney or partial pancreas

      Screen women with GDM to identify those at high risk of progression to type 1 DM

      Zinc transporter 8 (ZnT8)

      Differentiate latent autoimmune diabetes in adults (LADA) from type 2 DM

      Monitor progression to type 1 DM in preclinical phase

      Should be used in conjunction with tests for GAD65, insulin, and IA-2

      Islet cell antibody (ICA)

      Acceptable second-line test for type 1 DM if tests for GAD, IA-2, and ZnT8 abs are negative

      May be useful in determining multiple islet cell abs in at-risk children for type 1 DM

Differential Diagnosis

  • Type 2 DM
  • Type 1 DM (ketoacidosis)
  • GDM
    • Infection
    • Acute abdomen
      • Appendicitis
      • Cholecystitis/cholelithiasis
      • Pregnancy-related abdominal problem
        • Intrauterine infection
    • Hypoglycemia
    • Hyperglycemia
      • Infection
      • Acute abdomen
        • Appendicitis
        • Cholecystitis/cholelithiasis
        • Pregnancy-related abdominal problems
          • Intrauterine infection
    • Thyroid disease

Screening

Adults (one of the following)

  • Screening criteria for diabetes mellitus

    Screening Criteria for Diabetes Mellitus

    American Diabetes Association (2014)

    U.S. Preventive Services Task Force (2008)

    Testing should be considered in all adults who are overweight (BMI ≥25 kg/m2) and have additional risk factors:

    • Physical inactivity
    • First-degree relative with DM
    • Member of high-risk ethnic population (eg, African American, Latino)
    • Women who delivered a baby weighing >9 lb or were diagnosed with GDM
    • Hypertension (≥140/90 mmHg) or on antihypertensive therapy
    • HDL-C level <35 mg/dL and/or triglyceride level >250 mg/dL
    • Women with PCOS
    • HbA1c ≥5.7%, impaired glucose tolerance (IGT), or impaired fasting glucose (IFG) on previous testing
    • Other clinical conditions associated with insulin resistance (eg, severe obesity, acanthosis nigricans)
    • History of CVD

    In the absence of the above criteria, testing for DM should begin at 45 years

    • If results are normal, testing should be repeated at least every 3 years, with consideration of more frequent testing depending on initial results and risk status
    • Screening is recommended for type 2 DM in asymptomatic adults with sustained blood pressure (either treated or untreated) >135/80 mmHg
    • No recommendation for asymptomatic adults with blood pressure ≤135/80 mmHg

Pregnant women

  • Two approaches may be utilized – two-step or one-step 
  • ApproachCriteriaFasting mg/dL1-hr mg/dL2-hr mg/dL3-hr mg/dL
    Two-step (50-g, 100-g load) (NIH consensus)Carpenter & Coustan95 (5.3 mmol/L)180 (10.0 mmol/L)155 (8.6 mmol/L)140 (7.8 mmol/L)
    NDDG105 (5.8 mmol/L)190 (10.6 mmol/L)165 (9.2 mmol/L)145 (8.0 mmol/L)

    One-step (75-g load) (IADPSG consensus)

    IADPSG≥92 (5.1 mmol/L)≥180 (10 mmol/L)≥153 (8.5 mmol/L)n/a
    NDDG = National Diabetes Data Group; IADPSG = International Association of Diabetes and Pregnancy Study Groups
    Comparison of Diagnostic Testing Recommendations for GDM

    Comparison of Diagnostic Testing Recommendations for GDM

    Guidelines

    Glucose Load

    Diagnostic Threshold (mg/dL)

    IADPSG (2010)

    75-g, 2-hr OGTT performed at 24-28 weeks gestation in women not previously diagnosed with overt diabetes

    OGTT should be performed in morning after overnight fast of at least 8 hrs

    FPG ≥92, 1 hr ≥180, 2 hr ≥153

    Criteria met when any single point exceeded

    American Congress of Obstetricians and Gynecologists  (2013)

    Screen women early if high risk

    If using 1-hr screening, glucose threshold should be between 135-140

    Recommend 75-g, 2-hr OGTT performed at 24-28 weeks gestation

    FPG ≥92, 1 hr ≥180, 2 hr ≥153

    Criteria met when any single point exceeded [IADPSG criteria]

    U.S. Preventive Services Task Force (2014)

    One- or two-step screening (see ADA below)

    See ADA below

    American Diabetes Association (2014)

    One-step screening (IADPSG consensus) – 75-g, 2 hr OGTT

    OR

    Two-step screening (NIH consensus) – 50-g, 1 hr OGTT at step 1; 100-g, 3 hr OGTT at step 2 (two abnormal values)

    FPG ≥92, 1 hr ≥180, 2 hr ≥153

    CC: FPG 95, 1 hr 180, 2 hr 155, 3 hr 140

    OR

    NDDG: FPG 105, 1 hr 190, 2 hr 165, 3 hr 145

    Endocrine Society (2013)

    75-g, 2-hr OGTT performed at 24-28 weeks gestation

    FPG ≥92, 1 hr ≥180, 2 hr ≥153

    Criteria met when any single point exceeded [IADPSG criteria]

    NDDG = National Diabetes Data Group; IADPSG = International Association of Diabetes and Pregnancy Study Groups, CC = Carpenter/Coustan

Monitoring

Recommendations for physical examination (ADA, 2014)

  • Blood pressure – every routine visit, including orthostatic measurements when indicated (goal <140/80 mmHg)
  • Weight – every visit (goal is BMI <25 kg/m2)
    • Bariatric surgery may be considered if BM ≥35 kg/m2
  • Initial dilated and comprehensive eye exam by expert within 5 years of onset of DM for all adults and children ≥10 years (if first exam is normal, then every 2 years following normal eye exam)
  • Thyroid palpation
    • Important in type 1 DM – also consider antibody screening
  • Skin examination – for acanthosis nigricans and insulin injection sites
  • Neurological/foot examination
    • At diagnosis of type 2 DM; within 5 years after diagnosis of type 1 DM
    • Inspection of feet for lesions
    • Palpation of dorsalis pedis (DP) and posterior tibial (PT) artery pulses
    • Presence/absence of patellar and Achilles reflexes
    • Determination of proprioception, vibration (using 128 Hz tuning fork) and monofilament sensation testing
  • Celiac testing
    • Consider in patients with type 1 DM (particularly children)

Laboratory Testing

Glycemic control

Glycemic Control

HbA1c

  • Premise of testing
    • Glycation of hemoglobin is non-linear over time and occurs over the whole lifespan of the red blood cell
    • Correlates with risk of long-term complications and with DM control over previous 2-3 months
  • Target goal – <6.5-7% of glycated hemoglobin for most patients (ADA, 2014)
  • Laboratory testing recommendations 
    • 2 measurements per year for patients meeting goal of <6.5-7% (ADA, 2014), ≤6.5% (ACE/AACE)
      • If patient is not hypoglycemic, goal should be <6.5%
    • More frequent monitoring in patients with HbA1c ≥7%; however, not more often than every 3 months

1,5-Anhydroglucitol (GlycoMark)

  • Premise of testing
    • Renal reabsorption of 1.5-anhydroglucitol is competitively inhibited by glucose and is excreted in the urine when the concentration of plasma glucose exceeds its renal threshold (~180 mg/dL)
    • Poor glycemic control leads to decreased concentrations of plasma 1,5-anhydroglucitol
    • Less sensitive to small changes in glycemic control at high HbA1c levels
      • 1.5-AG reflects postprandial glycemic changes better than other glycemic indicators and measurements may be useful for assessing postprandial hyperglycemia
  • Laboratory testing recommendations
    • Not recommended for monitoring DM
    • May be useful for identifying postprandial hyperglycemia and assessing glycemic control in patients with moderately controlled diabetes
      • In patients with normal 1.5-AG (HbA1c 6.1-7.9%), treatment should be aimed at normalizing fasting blood glucose
      • In patients with low 1.5-AG, treatment should be aimed at normalizing postprandial glucose

Fructosamine

  • Premise of testing
    • Marker of glycemia (not short-term, like HbA1c)
    • Carbonyl group of glucose reacts with an amino group of a protein
    • Provides glycemia index over 20-day period
  • Laboratory testing recommendations
    • May be useful in monitoring GDM; not recommended for other types of DM
    • May be used in patients with shortened red cell survival (eg, sickle cell disease and other hemoglobinopathies)

Albumin, glycated

  • Premise of testing
    • Marker of glycemia (not short-term, like HbA1c)
    • Measures glycation of serum albumin
    • Provides glycemia index over 20-day period
  • Laboratory testing recommendations
    • May be useful in monitoring GDM; not recommended for other types of DM
    • May be used in patients with shortened red cell survival (eg, sickle cell disease)
    • Control in patients with moderately controlled diabetes

Insulin

  • Premise of testing
    • Circulating levels of insulin may be prognostic for likelihood of progression to insulin dependence in DM
  • Laboratory testing recommendations
    • Not recommended for monitoring or diagnosis of DM

C-peptide

  • Premise of testing
    • C-peptide connects the A & B chains of proinsulin
    • Released in equimolar concentrations with insulin
    • Reflects endogenous insulin production
  • Laboratory testing recommendations
    • Not recommended for monitoring or diagnosis of DM
    • May be useful for assessing endogenous insulin production to confirm need for insulin therapy
  • Dyslipidemia
    • Lipid panel (fasting)
      • Premise of testing
        • Patients with DM have an increased incidence of lipid abnormalities, creating risk for CVD
        • Lipid-lowering therapies have been demonstrated to reduce macrovascular disease
      • ADA target goals (2014)
        • LDL
          • <100 mg/dL – low risk patient
          • <70 mg/dL  – high risk patient
        • HDL
          • >40 mg/dL (men)
          • >50 mg/dL (women)
        • Triglycerides <150 mg/dL
      • Laboratory testing recommendations
        • Initial evaluation and annually thereafter if goals are met
          • More often if goals are not met
          • Adult with low values (LDL <100 mg/dL, HDL >50 mg/dL, triglycerides <150 mg/dL) – assessments up to two years apart
        • Treat aggressively with statins based on initial risk assessment (ACC/AHA 2013 guidelines)
          • No target goals set by ACC/AHA
  • Hepatic function
    • Premise of testing
      • Patients with DM are at risk for steatohepatitis
    • Laboratory testing recommendations
      • Liver function tests –  AST, ALT, alkaline phosphatase, and bilirubin
      • Initial evaluation and annually thereafter if values are normal on initial testing
  • Renal function
    • Creatinine 
      • Premise of testing
        • Many drugs require adjusted dosing based on creatinine, creatinine clearance or estimated glomerular filtration rates (eGFR) and DM may affect renal function in the course of the disease
        • Absolute creatinine values do not reflect glomerular filtration rates in many patients
          • Diabetic nephropathy diminishes creatinine clearance
          • Renal function thereby diminishes clearance and glomerular filtration rate
        • Creatinine and eGFR are broad measures of renal function
      • Laboratory testing recommendations
        • Serum creatinine and eGFR annually
    • Microalbumin (urine)
      • Premise of testing
        • Diabetic nephropathy occurs in 20-40% of patients with DM and is the single leading cause of end-stage renal disease – adding angiotensin converting enzyme (ACE) inhibitors reduces progression
        • Persistent albuminuria (range 30-299 mg/24 hours and levels ≥300 mg/24 hours) signifies the earliest stage of diabetic nephropathy
      • Target goal
        • <30 mg/24 hour urine (ADA, 2014)
      • Laboratory testing recommendations
        • Spot urine or 24-hour urine for microalbumin annually
  • Thyroid function
    • TSH, autoimmune antibodies
      • Premise of testing
      • Laboratory testing recommendations
        • Initial evaluation using TSH/antibody testing (for type 1 DM) and, if normal, TSH every 3 years thereafter
  • Other possible testing
    • Haptoglobin (HP) genotyping – predictor of CVD in diabetics
      • Hp1-1 genotype – predicts lowest risk
      • Hp2-2 genotype – predicts highest risk
      • Hp1-2 genotype – predicts intermediate risk

Clinical Background

Diabetes mellitus (DM) is a group of metabolic diseases resulting from defects in insulin secretion and/or insulin resistance that can lead to significant morbidity and mortality in affected patients.

Classification of Diabetes Mellitus

  • Type 1 DM – 90-95% in pediatric population; absolute insulin deficiency
  • Type 2 DM – most are teenagers or older; insulin resistance with or without insulin deficiency
  • Other types of DM due to other causes (eg, cystic fibrosis, drug-induced)
  • Gestational diabetes mellitus (GDM) – exclusive to pregnant females

Diabetes Mellitus Type 1

  • See Pediatrics tab

Diabetes Mellitus Type 2

  • Type 2 DM

    Epidemiology

    • Prevalence – affects >20 million in U.S.
      • 6.5% of population
    • Age – usually diagnosed >30 years
    • Sex – M:F, equal
    • Occurrence – increase in teenage obesity is associated with increased occurrence of DM type 2

    Inheritance

    • 75% concordance rate between identical twins
    • Several susceptibility genes have been identified

    Risk Factors

    • Obesity (BMI >25 kg/m2)
    • Family history of DM type 2 in first- or second-degree relative
    • Race/ethnicity – Native American, African American, Latino, Asian American, Pacific Islander
    • Signs of insulin resistance or conditions associated with insulin resistance (acanthosis nigricans, hypertension, dyslipidemia, polycystic ovarian syndrome (PCOS), low birth weight)
    • Maternal history of DM or GDM during child’s gestation

    Pathophysiology

    • Combination of progressive β-cell dysfunction with insulin secretory defect in a background of insulin resistance
    • No known autoimmune destruction of the pancreas

    Clinical Presentation

    • May have polyuria, polydipsia or polyphagia
    • Headache, fatigue, blurred vision, recurring Candida infections
    • More often presents with microvascular, macrovascular and neuropathic complications
      • Tingling, numbness in extremities
      • Lipid abnormalities
      • Renal insufficiency
    • Complications – hyperosmolar coma (uncommon)
      • Long-term complications

    Treatment

    • Insulin therapy required in type 1 and type 2 if patient presents with dehydration, ketosis, or acidosis

Gestational Diabetes Mellitus

  • GDM

    Epidemiology

    • Prevalence – 6-7% of all pregnancies (USPTSF, 2014)

    Risk Factors

    • History of previous GDM
    • Previous birth of baby >4.5 kg
    • Severe obesity
    • Strong family history of DM type 2
    • Diagnosis of PCOS

    Clinical Presentation

Pediatrics

Type 1 DM

Epidemiology

  • Prevalence
    • Varies by nationality – common in Northern European populations; uncommon in Chinese, Indian populations
    • 1/400-600 children and adolescents
  • Age
    • Majority diagnosed at or before adolescence
    • Peaks at 5-7 years and adolescence
  • Sex – M>F (slightly)
  • Inheritance
    • Interplay between genetic susceptibility and environmental factors

Pathophysiology

  • Caused by autoimmune mediated destruction of insulin-producing β-cells of the islets of Langerhans in the pancreas
  • Insulin regulates how the body stores and uses glucose
  • Absolute insulin deficiency of type 1 DM is a result of the following
    • Chronic inflammatory response against the islet cells
    • Cell mediated destruction of islet cells accompanied by production of islet cell antibodies 
      • Autoantibodies
        • Islet cell antibodies (ICA)
          • May be detected years prior to clinical symptoms
        • Glutamic acid decarboxylase (GAD65)
        • Insulinoma antigen 2 (IA-2)
        • Insulin autoantibodies (IAA)
        • Zinc transporter 8 (ZnT8)
      • Presence of these antibodies in individuals with diabetes confirms autoimmune etiology

Clinical Presentation

  • Polydipsia, polyuria, polyphagia
  • Nonspecific symptoms
    • Fatigue
    • Nausea, emesis
    • Weight loss
    • Blurred vision
  • Length of time from clinical presentation to diagnosis is typically a few weeks
  • Complications – diabetic ketoacidosis

 Type 2 DM

  • See Clinical Background section

Diagnosis

Indications for Testing

  • Fatigue, polyuria, polydipsia, weight loss

Criteria for Diagnosis

  • Refer to Diagnosis section

Laboratory Testing

  • Fasting plasma glucose, 2-hour oral glucose tolerance test (OGTT), and random glucose are the preferred tests to diagnose diabetes in children
    • HbA1c – use is supported by ADA (2014)
  • Use of C-peptide levels or insulin levels to diagnose diabetes is not recommended
  • Consider insulin antibody testing to help differentiate type 1 DM from type 2 DM
    • Refer to Diagnosis section

Screening 

  • Children with known risk factors (ADA, 2014) – screen at 10 years; repeat every 3 years if
    • BMI >85% and any 2 of the following
      • First- or second-degree relative with type 2 DM
      • Maternal history of DM or GDM
      • Member of at-risk minority group (eg, Native American, African American, Latino, Asian American, Pacific Islander)
      • Signs and symptoms of insulin resistance – PCOS, hypertension, acanthosis nigricans

Monitoring

  • HbA1c
    • Premise of testing
      • Glycation of hemoglobin is non-linear over time and occurs over the whole lifespan of the red blood cell
      • Correlates with risk of long-term complications and with diabetes control over previous 2-3 months
    • Target goal (ADA, 2014)
      • <8.5% for children <6 years
      • <8% for children 6-12 years
      • <7.5% for children 13-19 years
    • Laboratory testing recommendations 
      • 2 measurements per year for patients meeting goal of <6.5-7% (ADA, 2014), ≤6.5% (ACE/AACE)
        • If patient is not hypoglycemic, goal should be <6%
      • More frequent monitoring in patients with HbA1c ≥7%; however, not more often than every 3 months
  • Hypoglycemia
    • Not infrequent when children are using insulin
      • Diligence required for younger children

Indications for Laboratory Testing

  • Tests generally appear in the order most useful for common clinical situations
  • Click on number for test-specific information in the ARUP Laboratory Test Directory
Test Name and Number Recommended Use Limitations Follow Up
Glucose, Plasma or Serum 0020024
Method: Quantitative Enzymatic

Diagnose and manage DM and other carbohydrate metabolism disorders

Diagnosis of DM should be confirmed with a repeated test

   
Glucose Tolerance Test 0020542
Method: Quantitative Enzymatic

Diagnose DM, GDM, or impaired glucose tolerance

Components include glucose, fasting and glucose, 2-hour

   
Hemoglobin A1c 0070426
Method: Quantitative High Performance Liquid Chromatography/Boronate Affinity

Diagnose or monitor DM

Diagnosis should be confirmed with a repeated test

Monitor prediabetes

Unstable hemoglobins or hemolytic anemia may yield falsely low results

Iron deficiency anemia may yield falsely high results

 
Glucose Screen, Pregnancy 0020047
Method: Quantitative Enzymatic

Screen for GDM

   
Microalbumin, Urine 0050203
Method: Quantitative Immunoturbidimetry

Monitor diabetic nephropathy in DM

   
Lipid Panel 0020421
Method: Quantitative Enzymatic

Use for monitoring for dyslipidemia in DM

Panel includes total cholesterol, triglycerides, HDL cholesterol, LDL cholesterol (calculated), appearance, VLDL cholesterol (calculated)

   
Glomerular Filtration Rate, Estimated 0020725
Method: Quantitative Enzymatic

Use for monitoring for renal insufficiency in DM

   
Hepatic Function Panel 0020416
Method: Quantitative Enzymatic/Quantitative Spectrophotometry

Assess and monitor risk for steatohepatitis

Panel includes albumin, alkaline phosphatase, aspartate aminotransferase, alanine aminotransferase, bilirubin, and protein

   
Thyroid Stimulating Hormone with reflex to Free Thyroxine 2006108
Method: Quantitative Electrochemiluminescent Immunoassay
Assess and monitor risk for thyroid disease    
Thyroid Stimulating Immunoglobulin 0099430
Method: Quantitative Bioassay/Quantitative Chemiluminescent Immunoassay

Preferred testing for autoimmune thyroid disease (eg, GD) based on ARUP analytical sensitivities (versus TRAb sensitivities)

Prognostic marker for relapse of GD or remission following drug therapy

Support GD diagnosis in difficult (euthyroid) cases

Predict risk of thyroid dysfunction

Blocking antibodies specific to TSHR may decrease TSI antibody levels; net response is most likely physiologic

TSH serum levels ≥6 mU/L may cause a false-positive result

 
Thyroid Stimulating Hormone Receptor Antibody (TRAb) 2002734
Method: Quantitative Electrochemiluminescent Immunoassay

Acceptable testing for autoimmune thyroid disease

Aids in the differentiation of GD from factitious thyrotoxicosis, postpartum thyroiditis, or toxic nodular goiter

Prognostic marker for relapse of GD or remission following drug therapy

Predict risk of thyroid dysfunction in newborns of mothers with GD

Evaluate for the presence of euthyroid GD ophthalmopathy

   
Albumin, Glycated 0080700
Method: Quantitative Boronate Affinity Chromatography/Immunoturbidimetry

Use for monitoring GDM or shortened red-cell survival

   
Fructosamine 0099012
Method: Quantitative Spectrophotometry

Alternative, not first-line, means of monitoring DM

Variations in levels of serum proteins can affect results

High levels of ascorbic acid interfere with the assay

 
1,5 Anhydroglucitol Quantitative, Serum or Plasma 0081335
Method: Quantitative Enzymatic

Monitoring postprandial hyperglycemia and short-term glycemic control when hemoglobin A1c is 6.1-7.9%

Do not use in poorly controlled disease because test is not sensitive

In patients with poorly controlled DM 1,5-AG is less sensitive to modest changes in glycemic control due to continuous glycosuria

Decreased in individuals with renal glucose thresholds that are markedly different from 180 mg/dL (eg, chronic renal failure, pregnancy, dialysis) and in those undergoing steroid therapy

Alpha-glucosidase inhibitors can decrease 1,5-AG by interfering with intestinal absorption

 
Additional Tests Available
 
Click the plus sign to expand the table of additional tests.
Test Name and NumberComments
Zinc Transporter 8 Antibody 2006196
Method: Quantitative Enzyme-Linked Immunosorbent Assay

Differentiate latent autoimmune diabetes in adults (LADA) from type 2 DM

Monitor progression to type 1 DM in preclinical phase

Should be used in conjunction with tests for GAD65, insulin, and IA-2

Glutamic Acid Decarboxylase Antibody 2001771
Method: Quantitative Enzyme-Linked Immunosorbent Assay

Distinguish type 1 from type 2 DM in in children to institute insulin therapy at the time of diagnosis

Identify subset of adults with DM2 phenotype who progress rapidly to insulin dependency

Recommended in combination for initial screening of suspected cases of DM1

Screen nondiabetic family members who wish to donate a kidney or partial pancreas

Screen women with GDM to identify those at high risk of progression to DM1

IA-2 Antibody 0050202
Method: Quantitative Radioimmunoassay

Distinguish type 1 from type 2 DM in in children to institute insulin therapy at the time of diagnosis

Identify subset of adults with DM2 phenotype who progress rapidly to insulin dependency

Recommended in combination for initial screening of suspected cases of DM1

Screen nondiabetic family members who wish to donate a kidney or partial pancreas

Screen women with GDM to identify those at high risk of progression to DM1

Insulin Antibody 0099228
Method: Quantitative Radioimmunoassay

Distinguish type 1 from type 2 DM in in children to institute insulin therapy at the time of diagnosis

Identify subset of adults with DM2 phenotype who progress rapidly to insulin dependency

Screen nondiabetic family members who wish to donate a kidney or partial pancreas

Screen women with GDM to identify those at high risk of progression to DM1

Islet Cell Cytoplasmic Antibody, IgG 0050138
Method: Semi-Quantitative Indirect Fluorescent Antibody

Acceptable second-line test for DM1 if tests for GAD65, IA-2, and ZnT8 abs are negative

May be useful in determining multiple islet cell abs in at-risk children for DM1

C-Peptide, Serum or Plasma 0070103
Method: Quantitative Chemiluminescent Immunoassay

Not useful in DM monitoring

May aid in distinguishing DM1 from DM2

Insulin, Free and Total 0070155
Method: Quantitative Ultrafiltration/Quantitative Chemiluminescent Immunoassay

Not useful in DM monitoring

Insulin, Random 0070107
Method: Quantitative Chemiluminescent Immunoassay

Not useful in diagnosing or monitoring of DM

Insulin, Fasting 0070063
Method: Quantitative Chemiluminescent Immunoassay

Not useful in diagnosing or monitoring of DM

Haptoglobin (HP) Genotyping 0040116
Method: Polymerase Chain Reaction/Fluorescence Monitoring

Not useful in diagnosis or monitoring of DM

Screening for diabetic patients at risk for cardiovascular disease or diabetic patients considering cardiovascular treatment options