2. Classification and Diagnosis of Diabetes: Standards of Medical Care in Diabetes—2019
Article Figures & Tables
Figures
- Figure 2.1
ADA risk test (diabetes.org/socrisktest).
Tables
- Table 2.1
Staging of type 1 diabetes (4,5)
Stage 1 Stage 2 Stage 3 Characteristics Autoimmunity
Autoimmunity
New-onset hyperglycemia
Normoglycemia
Dysglycemia
Symptomatic
Presymptomatic
Presymptomatic
Diagnostic criteria Multiple autoantibodies
Multiple autoantibodies
Clinical symptoms
No IGT or IFG
Dysglycemia: IFG and/or IGT
Diabetes by standard criteria
FPG 100–125 mg/dL (5.6–6.9 mmol/L)
2-h PG 140–199 mg/dL (7.8–11.0 mmol/L)
A1C 5.7–6.4% (39–47 mmol/mol) or ≥10% increase in A1C
- Table 2.2
Criteria for the diagnosis of diabetes
FPG ≥126 mg/dL (7.0 mmol/L). Fasting is defined as no caloric intake for at least 8 h.* OR 2-h PG ≥200 mg/dL (11.1 mmol/L) during OGTT. The test should be performed as described by the WHO, using a glucose load containing the equivalent of 75-g anhydrous glucose dissolved in water.* OR A1C ≥6.5% (48 mmol/mol). The test should be performed in a laboratory using a method that is NGSP certified and standardized to the DCCT assay.* OR In a patient with classic symptoms of hyperglycemia or hyperglycemic crisis, a random plasma glucose ≥200 mg/dL (11.1 mmol/L). ↵* In the absence of unequivocal hyperglycemia, diagnosis requires two abnormal test results from the same sample or in two separate test samples.
- Table 2.3
Criteria for testing for diabetes or prediabetes in asymptomatic adults
1. Testing should be considered in overweight or obese (BMI ≥25 kg/m2 or ≥23 kg/m2 in Asian Americans) adults who have one or more of the following risk factors: • First-degree relative with diabetes
• High-risk race/ethnicity (e.g., African American, Latino, Native American, Asian American, Pacific Islander)
• History of CVD
• Hypertension (≥140/90 mmHg or on therapy for hypertension)
• HDL cholesterol level <35 mg/dL (0.90 mmol/L) and/or a triglyceride level >250 mg/dL (2.82 mmol/L)
• Women with polycystic ovary syndrome
• Physical inactivity
• Other clinical conditions associated with insulin resistance (e.g., severe obesity, acanthosis nigricans)
2. Patients with prediabetes (A1C ≥5.7% [39 mmol/mol], IGT, or IFG) should be tested yearly. 3. Women who were diagnosed with GDM should have lifelong testing at least every 3 years. 4. For all other patients, testing should begin at age 45 years. 5. If results are normal, testing should be repeated at a minimum of 3-year intervals, with consideration of more frequent testing depending on initial results and risk status. - Table 2.4
Risk-based screening for type 2 diabetes or prediabetes in asymptomatic children and adolescents in a clinical setting
Testing should be considered in youth* who are overweight (≥85% percentile) or obese (≥95 percentile) A and who have one or more additional risk factors based on the strength of their association with diabetes:
• Maternal history of diabetes or GDM during the child's gestation A
• Family history of type 2 diabetes in first- or second-degree relative A
• Race/ethnicity (Native American, African American, Latino, Asian American, Pacific Islander) A
• Signs of insulin resistance or conditions associated with insulin resistance (acanthosis nigricans, hypertension, dyslipidemia, polycystic ovary syndrome, or small-for-gestational-age birth weight) B
↵* After the onset of puberty or after 10 years of age, whichever occurs earlier. If tests are normal, repeat testing at a minimum of 3-year intervals, or more frequently if BMI is increasing, is recommended.
- Table 2.5
Criteria defining prediabetes*
FPG 100 mg/dL (5.6 mmol/L) to 125 mg/dL (6.9 mmol/L) (IFG) OR 2-h PG during 75-g OGTT 140 mg/dL (7.8 mmol/L) to 199 mg/dL (11.0 mmol/L) (IGT) OR A1C 5.7–6.4% (39–47 mmol/mol) ↵* 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.
- Table 2.6
Screening for and diagnosis of GDM
One-step strategy
Perform a 75-g OGTT, with plasma glucose measurement when patient is fasting and at 1 and 2 h, at 24–28 weeks of gestation in women not previously diagnosed with diabetes.
The OGTT should be performed in the morning after an overnight fast of at least 8 h.
The diagnosis of GDM is made when any of the following plasma glucose values are met or exceeded:• Fasting: 92 mg/dL (5.1 mmol/L)
• 1 h: 180 mg/dL (10.0 mmol/L)
• 2 h: 153 mg/dL (8.5 mmol/L)
Two-step strategy
Step 1: Perform a 50-g GLT (nonfasting), with plasma glucose measurement at 1 h, at 24–28 weeks of gestation in women not previously diagnosed with diabetes.
If the plasma glucose level measured 1 h after the load is ≥130 mg/dL, 135 mg/dL, or 140 mg/dL (7.2 mmol/L, 7.5 mmol/L, or 7.8 mmol/L, respectively), proceed to a 100-g OGTT.
Step 2: The 100-g OGTT should be performed when the patient is fasting.
The diagnosis of GDM is made if at least two* of the following four plasma glucose levels (measured fasting and 1 h, 2 h, 3 h during OGTT) are met or exceeded:Carpenter-Coustan (86) or NDDG (87) • Fasting
95 mg/dL (5.3 mmol/L) 105 mg/dL (5.8 mmol/L) • 1 h
180 mg/dL (10.0 mmol/L) 190 mg/dL (10.6 mmol/L) • 2 h
155 mg/dL (8.6 mmol/L) 165 mg/dL (9.2 mmol/L) • 3 h
140 mg/dL (7.8 mmol/L) 145 mg/dL (8.0 mmol/L) NDDG, National Diabetes Data Group. *ACOG notes that one elevated value can be used for diagnosis (82).
- Table 2.7
Most common causes of monogenic diabetes (119)
Gene Inheritance Clinical features MODY GCK AD GCK-MODY: stable, nonprogressive elevated fasting blood glucose; typically does not require treatment; microvascular complications are rare; small rise in 2-h PG level on OGTT (<54 mg/dL [3 mmol/L]) HNF1A AD HNF1A-MODY: progressive insulin secretory defect with presentation in adolescence or early adulthood; lowered renal threshold for glucosuria; large rise in 2-h PG level on OGTT (>90 mg/dL [5 mmol/L]); sensitive to sulfonylureas HNF4A AD HNF4A-MODY: progressive insulin secretory defect with presentation in adolescence or early adulthood; may have large birth weight and transient neonatal hypoglycemia; sensitive to sulfonylureas HNF1B AD HNF1B-MODY: developmental renal disease (typically cystic); genitourinary abnormalities; atrophy of the pancreas; hyperuricemia; gout Neonatal diabetes KCNJ11 AD Permanent or transient: IUGR; possible developmental delay and seizures; responsive to sulfonylureas INS AD Permanent: IUGR; insulin requiring ABCC8 AD Permanent or transient: IUGR; rarely developmental delay; responsive to sulfonylureas 6q24 (PLAGL1, HYMA1) AD for paternal duplications Transient: IUGR; macroglossia; umbilical hernia; mechanisms include UPD6, paternal duplication or maternal methylation defect; may be treatable with medications other than insulin GATA6 AD Permanent: pancreatic hypoplasia; cardiac malformations; pancreatic exocrine insufficiency; insulin requiring EIF2AK3 AR Permanent: Wolcott-Rallison syndrome: epiphyseal dysplasia; pancreatic exocrine insufficiency; insulin requiring FOXP3 X-linked Permanent: immunodysregulation, polyendocrinopathy, enteropathy X-linked (IPEX) syndrome: autoimmune diabetes; autoimmune thyroid disease; exfoliative dermatitis; insulin requiring AD, autosomal dominant; AR, autosomal recessive; IUGR, intrauterine growth restriction.
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