Screening for Type 1 and Type 2 Diabetes

Canadian Diabetes Association Clinical Practice Guidelines Expert Committee

Jean-Marie Ekoé MD, CSPQ, PD Zubin Punthakee MD, MSc, FRCPC Thomas Ransom MD, MSc, FRCPC Ally P.H. Prebtani BScPhm, MD, FRCPC Ronald Goldenberg MD, FRCPC, FACE

  • Key Messages
  • Recommendations
  • Figures
  • Highlights
  • Full Text
  • References

Key Messages

  • In the absence of evidence for interventions to prevent or delay type 1 diabetes, screening for type 1 diabetes is not recommended.
  • Screening for type 2 diabetes using a fasting plasma glucose (FPG) and/or glycated hemoglobin (A1C) should be performed every 3 years in individuals ≥40 years of age or in individuals at high risk using a risk calculator.
  • Diabetes will be diagnosed if A1C is ≥6.5% (see Definition, Classification and Diagnosis chapter, p. S8).
  • Testing with a 2-hour plasma glucose (2hPG) in a 75 g oral glucose tolerance test (OGTT) should be undertaken in individuals with an FPG of 6.1–6.9 mmol/L and/or an A1C of 6.0%–6.4% in order to identify individuals with impaired glucose tolerance (IGT) or diabetes.
  • Testing with a 2hPG in a 75 g OGTT may be undertaken in individuals with an FPG 5.6–6.0 mmol/L and/or A1C 5.5%–5.9% and ≥1 risk factor in order to identify individuals with IGT or diabetes.

Highlights of Revisions

  • Screening recommendations have been revised and strengthened to include glycated hemoglobin (A1C) levels to better identify individuals with prediabetes or diabetes.
Table 1
Risk factors for type 2 diabetes
A1C, glycated hemoglobin; HAART, highly active antiretroviral therapy; HDL, high-density lipoprotein; HIV, human immunodeficiency virus-1; IFG, impaired fasting glucose; IGT, impaired glucose tolerance; OSA, obstructive sleep apnea.
 Associated with insulin resistance.
 The incidence of type 2 diabetes is at least 3 times higher in people with schizophrenia than in the general population (25,26). Using data collected in 1991, the prevalence of diabetes was assessed in >20,000 individuals diagnosed with schizophrenia. The rate of diagnosed diabetes was 9% to 14%, exceeding rates for the general population prior to the widespread use of new antipsychotic drugs (27).
 HIV and HAART increase the risk of prediabetes (IGT) and type 2 diabetes by 1.5- to 4-fold compared to the general population (28).
§ OSA is an independent risk factor for diabetes (hazard ratio 1.43) (29).
  • Age ≥40 years
  • First-degree relative with type 2 diabetes
  • Member of high-risk population (e.g. Aboriginal, African, Asian, Hispanic or South Asian descent)
  • History of prediabetes (IGT, IFG or A1C 6.0%–6.4%) ∗
  • History of gestational diabetes mellitus
  • History of delivery of a macrosomic infant
  • Presence of end organ damage associated with diabetes:
    • >Microvascular (retinopathy, neuropathy, nephropathy)
    • Macrovascular (coronary, cerebrovascular, peripheral)
  • Presence of vascular risk factors:
    • HDL cholesterol level <1.0 mmol/L in males, <1.3 mmol/L in females ∗
    • Triglycerides ≥1.7 mmol/L ∗
    • Hypertension∗
    • Overweight ∗
    • Abdominal obesity ∗
  • Presence of associated diseases:
    • Polycystic ovary syndrome ∗
    • Acanthosis nigricans ∗
    • Psychiatric disorders (bipolar disorder, depression, schizophrenia )
    • HIV infection
    • OSA §
  • Use of drugs associated with diabetes:
    • Glucocorticoids
    • Atypical antipsychotics
    • HAART
    • Other (see Appendix 1)
  • Other secondary causes (see Appendix 1)

Recommendations

  1. All individuals should be evaluated annually for type 2 diabetes risk on the basis of demographic and clinical criteria [Grade D, Consensus].
  2. Screening for diabetes using FPG and/or A1C should be performed every 3 years in individuals ≥40 years of age or at high risk using a risk calculator [Grade D, Consensus]. More frequent and/or earlier testing with either FPG and/or A1C or 2hPG in a 75 g OGTT should be considered in those at very high risk using a risk calculator or in people with additional risk factors for diabetes [Grade D, Consensus]. These risk factors include:
    • First-degree relative with type 2 diabetes
    • Member of high-risk population (e.g. Aboriginal, African, Asian, Hispanic or South Asian descent)
    • History of prediabetes (IGT, IFG, or A1C 6.0%–6.4%)
    • History of gestational diabetes mellitus
    • History of delivery of a macrosomic infant
    • Presence of end organ damage complications associated with diabetes:
      • Microvascular (retinopathy, neuropathy, nephropathy)
      • Macrovascular (coronary, cerebrovascular, peripheral)
    • Presence of vascular risk factors:
      • HDL cholesterol <1.0 mmol/L in males, <1.3 mmol/L in females
      • Triglycerides ≥1.7 mmol/L
      • Hypertension
      • Overweight
      • Abdominal obesity
    • Presence of associated diseases:
      • Polycystic ovary syndrome
      • Acanthosis nigricans
      • Obstructive sleep apnea
      • Psychiatric disorders (bipolar disorder, depression, schizophrenia)
      • HIV infection
    • Use of drugs associated with diabetes:

      • Glucocorticoids
      • Atypical antipsychotics
      • HAART
      • Other
    • Other secondary causes
  3. Testing with 2hPG in a 75 g OGTT should be undertaken in individuals with FPG 6.1–6.9 mmol/L and/or A1C 6.0%–6.4% in order to identify individuals with IGT or diabetes [Grade D, Consensus].
  4. Testing with 2hPG in a 75 g OGTT may be undertaken in individuals with FPG 5.6–6.0 mmol/L and/or A1C 5.5%–5.9% and ≥1 risk factor(s) in order to identify individuals with IGT or diabetes [Grade D, Consensus].

Abbreviations:
2hPG, 2-hour plasma glucose; A1C, glycated hemoglobin; FPG, fasting plasma glucose; HAART, highly active antiretroviral therapy; HDL, high-density lipoprotein; HIV, human immunodeficiency virus-1; IFG, impaired fasting glucose; IGT, impaired glucose tolerance; OGTT, oral glucose tolerance test.

Figure 1
Screening and diagnosis algorithm for type 2 diabetes.

*If both fasting plasma glucose (FPG) and glycated hemoglobin (A1C) are available but discordant, use the test that appears furthest to the right side of the algorithm.
**Prediabetes = impaired fasting glucose (IFG), impaired glucose tolerance (IGT), or A1C 6.0% to 6.4% (see Table 4 in Definition, Classification and Diagnosis of Diabetes, Prediabetes and Metabolic Syndrome, p. S8). In the absence of symptomatic hyperglycemia, if a single laboratory test is in the diabetes range, a repeat confirmatory test (FPG, A1C, 2hPG in a 75 g OGTT) must be done on another day. It is preferable that the same test be repeated (in a timely fashion) for confirmation. If results of 2 different tests are available and both are above the diagnostic cutpoints, the diagnosis of diabetes is confirmed. NA = not available; OGTT = oral glucose tolerance test.

References

  1. McKee HA, D’Arcy PF, Wilson PJ. Diabetes and schizophrenia: a preliminary study. J Clin Hosp Pharm 1986;11:297e9.
  2. Mukherjee S, Decina P, Bocola V, et al. Diabetes mellitus in schizophrenic 108 patients. Compr Psychiatry 1996;37:68e73.
  3. Dixon L, Weiden P, Delahanty J, et al. Prevalence and correlates of diabetes in national schizophrenia samples. Schizophr Bull 2000;26:903e12.
  4. SamarasK,ChisholmDJ.Diabetes,insulinresistanceandglucosemetabolisminHIV infection and its treatment. In: Ekoe JM, Rewers M, Williams R, et al., editors.
  5. Botros N, Concato J, Mohsenin V, et al. Obstructive sleep apnea as a risk factor for type 2 diabetes. Am J Med 2009;122:1122e7.

 

Reproduced with permission from Canadian Journal of Diabetes © 2013 Canadian Diabetes Association. To cite this article, please refer to For citation.

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