Diabetes Screening (Canadian 2012 Guideline)

Rational

Screening adults at high-risk for diabetes results in reduction of MIs, microvascular complications, and death

Epidemiology

In 2008-2009: 6.8% of Canadians have the diagnosis of diabetes, and 1.4% were speculated to be undiagnosed but affected

Since 1998-1999 the prevalence of diabetes has increased by 70%

Screening

Use the FINDRISC or CANRISK score to risk stratify:

  • low- and moderate-risk individuals (1-17% chance of developing diabetes in 10 years) do not need to be screening, but repeat risk calculation every 3-5 years
  • high-risk (33% chance of developing diabetes in 10 years) individuals should be screened at least every 3-5 years
  • consider annual screening for very high-risk individuals (50% chance of developing diabetes in 10 years)

Diagnostic Criteria

Hb A1C ≥6.5% on a single measurement.

FBS ≥7.0 mmol/L

RBS ≥11.1 mmol/L

2-hr plasma glucose in a 75-g OGTT ≥11.1 mmol/L

Classification

“Prediabetes”: impaired fasting glucose or impaired glucose tolerance, but does not meet diagnostic criteria for diabetes.  These patients are at very high risk of developing diabetes over the next 10 years.

Risk Factors

Obesity, FHx, gestational diabetes, HTN, sedentary lifestyle

Investigations

A1C ($6-8) measurement is now considered the accepted screening test of choice.  If A1C ≥6.5%, a diagnosis of diabetes can be made.

FBS ($6-10) and OGTT ($30) may also be used as screening tests.

Management

Lifestyle interventions: diet (consider dietitian referral), increased activity, wt loss, cardiovascular risk factor modifications (quit smoking, HTN control, manage dyslipidemia)

Treatment

See Diabetes Management

Prognosis

Good if managed well.  Poorly managed diabetes includes the triad of nephropathy, retinopathy, and neuropathy.  Other potential and unfortunate complications include diabetic foot, increased risk for MI and stroke, and gastrointestinal motility issues.

65-80% of patients with diabetes die of a cardiovascular event, often without any signs or Sx of cardiovascular disease before the event.

References

Recommendation on screening for Type II diabetes in adults. Canadian Task Force on Preventative Health. CMAJ, October 16, 2012, 184(15), pages 1687-1696