Diagnostic Criteria

Diabetes Mellitus:

Diagnosis of diabetes mellitus cannot be made based on clinical symptoms alone. It also requires laboratory confirmation of abnormal blood glucose levels.

The diagnostic criteria are listed in Table 2 below:

Table 2 – Criteria for the diagnosis of diabetes*In the absence of symptoms of hyperglycemia, diagnosis requires two abnormal test results from the same sample or in two separate test samples.**Marked discordance between measured A1c and plasma glucose levels should raise the possibility of A1c assay interference due to a variety of factors/conditions such as those that prolong or decrease erythrocyte turnover (e.g. sickle cell disease, hemoglobinopathies, blood transfusions, G6PD deficiency), pregnancy, lead poisoning, certain chronic medication ingestions or vitamin supplements. (Radin, 2014) – in these cases, only plasma blood glucose criteria should be utilized for diagnosis of diabetes

Unequivocal classic symptoms of hyperglycemia or hyperglycemic crisis with a random plasma glucose of  >200mg/dL

OR

Fasting plasma glucose ≥ 126mg/dL, where fasting is defined as no caloric intake for at least 8 hrs*

OR

A1c > 6.5%**, performed in a certified lab and not by point-of-care methodologies*

OR

2-hr plasma glucose ≥ 200mg/dL after a 75g (1.75g/kg) oral glucose load (by oral glucose tolerance test = OGTT) *

There is a spectrum of clinical scenarios along which diabetes may be identified, as seen in Figure 3 below:

Diagnosis of diabetes lies on a spectrum that spans from low-risk individuals with incidental lab findings (located on the far left of the spectrum), high-risk individuals identified by screening-labs (middle of the spectrum), and symptomatic individuals identified with urgent lab testing (at the far right end of the spectrum).
Figure 3 – Spectrum of diagnostic clinical scenarios

Low-risk individuals and high-risk individuals who do not have classic symptoms of hyperglycemia need a second laboratory method that confirms the presence of persistent hyperglycemia.

Isolated or transient periods of hyperglycemia due to stress, surgery, infection, or medications can otherwise lead to the premature or inappropriate diagnosis of diabetes in these individuals.

Prediabetes:

Prediabetes  = individuals with blood glucose too high to be considered normal but not meeting diagnostic diabetes thresholds

The diagnostic criteria for prediabetes are demonstrated in Table 3 below:

Table 3- Diagnostic Criteria of Prediabetes
Fasting plasma glucose of 100 mg/dL to 125mg/dL (impaired fasting glucose)
OR
2-hr plasma glucose of 140mg/dL to 199mg/dL after a 75g (1.75g/kg) oral glucose load (by oral glucose tolerance test = OGTT)  (impaired glucose tolerance)
OR
A1c 5.7 – 6.4%
Diabetic Ketoacidosis (DKA):

If symptoms of diabetic ketoacidosis are present, then additional laboratory evaluation should be urgently pursued to confirm the diagnosis.

This is accomplished by assessing for the presence of severe hyperglycemia (plasma glucose), serum or urine ketones (serum beta-hydroxybutyrate, urine ketone dipstick, or urinalysis), and acidosis (venous blood gas and/or serum bicarbonate level).

Diagnosis of DKA requires the following:

Figure 4 – DKA Diagnostic Criteria

The severity of DKA can be further defined based on the thresholds of pH or serum bicarbonate presented in Table 4.

Table 4  – Severity of DKA and Diagnostic Criteria of Hyperosmolar hyperglycemic state (HHS)

Mild DKA

Moderate DKA

Severe DKA

HHS
Venous pH

7.3 – 7.2

7.1 – 7.19

<7.09

>7.25 (>7.3 arterial)
Serum bicarbonate (CO2)

<15 mEq/L

<10 mEq/L

<5mEq/L

>15 mEq/L
Ketones

Positive

Positive

Positive

Absent to Small
Plasma glucose

>200mg/dL

>200mg/dL

>200mg/dL

>600mg/dL
Effective serum osmolality

Variable

Variable

Variable

>320 mOsm/kg

Ketones may occur without significant acidosis (thus not meeting the criteria for DKA). In diabetic patients with absolute insulin deficiency, the absence of insulin leads to runaway ketone production and eventual pathological acidosis if not addressed quickly.

The following two conditions may occur in diabetics, but their presentations differ. Click on each to learn more!

Quiz Yourself:

Bibliography:

  1. ElSayed, N. A., Aleppo, G., Aroda, V. R., Bannuru, R. R., Brown, F. M., Bruemmer, D., . . . on behalf of the American Diabetes, A. (2023). 2. Classification and Diagnosis of Diabetes: Standards of Care in Diabetes-2023. Diabetes Care, 46(Suppl 1), S19-s40. doi:10.2337/dc23-S002
  2. Glaser N, Fritsch M, Priyambada L, Rewers A, Cherubini V, Estrada S, Wolfsdorf JI, Codner E. ISPAD clinical practice consensus guidelines 2022: Diabetic ketoacidosis and hyperglycemic hyperosmolar state. Pediatr Diabetes. 2022 Nov;23(7):835-856. doi: 10.1111/pedi.13406. PMID: 36250645.
  3. Libman I, Haynes A, Lyons S, Pradeep P, Rwagasor E, Tung JY, Jefferies CA, Oram RA, Dabelea D, Craig ME. ISPAD Clinical Practice Consensus Guidelines 2022: Definition, epidemiology, and classification of diabetes in children and adolescents. Pediatr Diabetes. 2022 Dec;23(8):1160-1174. doi: 10.1111/pedi.13454. PMID: 36537527.
  4. Radin, M. S. (2014). Pitfalls in hemoglobin A1c measurement: when results may be misleading. Journal of General Internal Medicine, 29(2), 388-394. doi:10.1007/s11606-013-2595-x

 

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General Inpatient Management of Pediatric Diabetes Mellitus at University of Iowa Stead Family Children's Hospital Copyright © 2023 by Alex Tuttle is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License, except where otherwise noted.

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