Effective Date: September 1, 2010
Full Guideline in PDF
Recommendations and Topics
This guideline describes the care objectives for the prevention, diagnosis and management of diabetes mellitus (DM) in non-pregnant adults. It focuses on the approaches and systems that are ideally in place to improve care for the majority of patients the majority of the time.
Diagnostic Code: 250 - Diabetes mellitus
Prevention and Risk Factors
Safe and effective therapies for the prevention of type 1 DM have not yet been identified.1 The risk for developing type 1 DM is influenced by family history of type 1 DM and other autoimmune diseases.
A large proportion of type 2 DM can be prevented using lifestyle modification and/or pharmacologic intervention.1 Lifestyle modification is particularly important for persons considered at high-risk, and pharmacologic therapy with metformin or acarbose can also be considered for patients with impaired glucose tolerance (IGT).2,3 Risk factors for type 2 DM include but are not limited to: obesity; age ≥40 years; close relative with type 2 DM; member of a high risk population (Aboriginal, Hispanic, South Asian, Asian, or African descent); history of IGT or impaired fasting glucose (IFG) and other conditions associated with insulin resistance (e.g. dyslipidemia, hypertension, abdominal obesity, vascular disease, schizophrenia and use of antipsychotic medications).4
The classic diagnostic symptoms for DM are polyuria, polydipsia, and unexplained weight loss with a "casual"* plasma glucose (PG) ≥11.1 mmol/L. In the absence of classic symptoms, a fasting† plasma glucose (FPG) is the recommended initial test in the diagnosis of diabetes. Glycosylated hemoglobin (A1C) has been proposed as a diagnostic test for type 2 diabetes; however, has not universally been adopted.5 See Appendix A Screening Algorithm for Type 2 DM in Adults.
*Casual=any time of day, regardless of the interval since the last meal. †Fasting= no caloric intake for at least 8 hours
Lifestyle Management of DM*
- Encourage a long-term healthy diet, recognizing diverse diets and needs.
- Calculate and optimize patient's BMI (mass in kilograms/height in metres2)
Target BMI: 18.5-24.9 kg/m2
Note that desirable BMI range may be lower for certain populations, (e.g. Asian, Pacific).
- Measure and optimize patient's waist circumference (WC).
Targets for WC: M ≤ 94 cm; F ≤ 80 cm (Europid, Sub-Saharan African, Eastern Mediterranean and Middle Eastern); M ≤ 90 cm; F ≤ 80 cm (South Asian, Chinese, Japanese, South and Central American)6.
- Encourage aerobic exercise (30 min/day) and resistance exercise (i.e. weights) 3 sessions/week. Aerobic exercise and/or resistance training may also benefit elderly people with type 2 DM and can be recommended if not contraindicated. Consider an ECG stress test for previously sedentary people with additional risk factors for CVD who wish to undertake exercise more vigorous than brisk walking.
- At each visit encourage patient to stop smoking; provide support as needed.
- Educate patients regarding basic clinical management measurements such as blood glucose, glycosylated hemoglobin (A1C), BP (blood pressure), and lipid profile. Encourage patients to accept responsibility for the care of their DM and develop a mutually acceptable management plan, including an identified primary care provider and individualized self-monitoring of blood glucose (SMBG). See Controversies in Care: SMBG.
- Consider referral to a Diabetes education clinic.
Management of Hyperglycemia and Hypoglycemia
- Focus is on achieving target A1C levels and on minimizing symptomatic hyper- and hypoglycemia.
Please refer to Appendix B for the Management of Hyperglycemia in type 2 DM, including details on when to initiate oral hypoglycemic medications or insulin without a 2-3 month trial of lifestyle modifications alone.
Appendix C: Antidiabetic Agents and Adjunctive Agents for Use in Type 2 DM
Appendix D: Insulin Therapeutic Considerations and Availability
- Hypoglycemia can be serious complication of therapy. Consider less stringent glycemic targets in patients at risk.
- Risk factors: Prior episode of severe hypoglycemia, long-term DM, current low A1C (<6.0%), autonomic neuropathy, hypoglycemia unawareness, current treatment with insulin, and being elderly. Severe hypoglycemia is less common in persons with type 2 DM but the elderly and those on insulin or secretagogues are more vulnerable.
- Prevention: Educate patients and families about prevention, detection and treatment of hypoglycemia. See Patient Education and Resources.
- To reduce the risk of hypoglycemia: increase the frequency of SMBG (including episodic assessment during sleeping hours), make glycemic targets less stringent, and consider multiple insulin injections.
Treatment: See Appendix E: Treatment of Hypoglycemia.
Preventing complications and comorbidities of DM
Healthy elderly people with DM may be treated to achieve the same targets as younger people, e.g. glucose control, BP, and lipids. Consider more conservative targets in people with multiple comorbidities, a high level of functional dependency, or limited life expectancy.
- BP control is a priority; measure and record at diagnosis and regularly thereafter: optimize to ≤130/80.7
- If lifestyle modification is not sufficient, choose from the following first-line agents: a thiazide diuretic, ACEI/ ARB, cardioselective B-blocker.
Blood Glucose: Long-term control
Studies suggest there is a long-term "legacy" benefit of glucose lowering early in the course of type 1 & 2 DM.8,9
- Measure glycosylated hemoglobin (A1C) every three months to ensure that glycemic goals are being met or maintained. Target for most patients A1C ≤7.0% (See Controversies in Care).
- Consider testing every 6 months if treatment and lifestyle remains stable and if targets have been consistently met.
- Focus on minimizing symptomatic hypo- and hyperglycemia, in addition to A1C levels.
Blood Glucose: SMBG*
- Reinforce patient's responsibility for regular monitoring as appropriate; ensure patients can use glucose meter, interpret results and modify treatment as needed. See Controversies in Care.
- Develop a blood glucose-monitoring schedule with patient and review records. SMBG is more important when using a drug that can cause hypoglycemia. Targets for most patients: Premeal =4.0 - 7.0 mmol/L: 2h Postmeal =5.0 - 10.0 mmol/L (more lenient targets can be used in patients with history of hypoglycemia or the elderly).
- Annual accuracy verification of glucose meter (simultaneous fasting glucose meter/lab comparison within 20%).
* Blood glucose test strips are a Pharmacare benefit for those holding a valid Certificate of Training in self-monitoring of blood glucose from a BC diabetes education centre.
- Measure fasting lipid profile (TC, HDL-C, LDL-C, triglycerides) initially. If within target without therapy then consider rechecking q1-3 years as clinically indicated.
- In patients receiving lipid treatment measure lipids within 6 to 8 weeks of initiation or change of pharmacotherapy and every 6 to 8 months thereafter (CK and ALT are the recommended safety tests)
- Apolipoprotein B (ApoB) can be used in place of lipid profiles for ongoing monitoring of therapy.
- Lipid targets must relate to the calculated risk, individualized to each patient, of developing CHD - although the majority of diabetic patients are high risk (see Controversies in Care). To estimate the 10-year risk of CHD for patients with type 2 DM use the UK prospective diabetes (UKPDS) risk calculator or table, available at: www.dtu.ox.ac.uk/riskengine/
|Lipid Targets (LDL-C or ApoB) According to CHD Risk Category*
(<20% 10-year risk)
(≥20% 10-year risk)
*LDL-C target of <2.0 or ApoB <0.8 (or a 50% LDL-C decrease from the baseline value) has been suggested by the new CCS guidelines10 for individuals in the moderate risk category with LDL-C >3.5 or ApoB >1.0. (See Controversies in Care).
- Consider low dose ASA (81-325 mg) for people with stable cardiovascular disease. The decision to prescribe antiplatelet therapy for primary prevention of CV events should be based on individual clinical judgement.11
- Consider employing ACEI for any patient over 55 years of age, patients with hypertension or patients with confirmed albuminuria.12
Early recognition and treatment of retinopathy can prevent blindness.
- Ensure patient receives dilated pupil retinal examination at diagnosis, then every one to two years or as indicated (annual referral to optometrist/ophthalmologist).
- Screen for macroscopic proteinuria & non-renal disease with urine dipstick.
- If protein-negative dipstick measure albumin/creatinine ratio (ACR): If ACR is equivocal, repeat collection; treat ACR if persistently above normal threshold.
- Measure SCr (lab will report eGFR) at least annually. See Chronic Kidney Disease - Identification, Evaluation and Management of Patients.
- Treatment may not normalize subsequent ACRs or eGFR.
- Stages of classic diabetic nephropathy according to ACR (mg/mmol):
- Normal: M <2.0; F <2.8; Micro-albuminuria (equivocal): M 2-20; F 2.8-28
- Overt Nephropathy: M >20; F >28
The best way to prevent diabetic neuropathy is to regularly monitor and manage blood glucose.
- Check annually for symptoms or findings such as peripheral anesthesic neuropathy or pain, or autonomic neuropathy e.g. erectile dysfunction, gastrointestinal disturbance, orthostatic hypotension.
- Include screening via monofilament during foot exam.
- Examine feet annually, and more frequently for those at high risk (i.e. patients with anesthetic neuropathy).
- Encourage regular self-examination of feet.
Psychosocial Aspects of Diabetes
Challenging psychosocial factors affect many aspects of diabetes management and glycemic control.
- Screen for depression, anxiety and eating disorders. Treatment of these conditions may improve outcomes.13
- Cognitive behaviour therapy (CBT) based techniques such as stress management strategies and coping skills can be implemented to improve outcomes.14
- Annual influenza vaccination.
- Pneumococcal vaccination: A single re-vaccination is recommended if the patient is >65 and previous vaccination was more than 5 years ago.
Additional Practice Points
Type 1 DM
- Patients with type 1 diabetes should see an experienced DM care team at diagnosis and at least annually.
- Insulin use: Multiple (3-4) daily injections or the use of continuous subcutaneous insulin infusions (CSII) should be considered as part of an intensive diabetes management program.
Type 2 DM
- See Appendix B Management of Hyperglycemia in Type 2 Diabetes.
- In elderly people with type 2 DM:
- Polypharmacy: review medication list periodically, particularly if the patient presents with depression, falls, cognitive impairment, perceptual difficulties, or urinary incontinence.
- Sulfonylureas: (especially glyburide) use with caution because the risk of hypoglycemia increases with age. Generally initial doses can be half of those for younger people and increased more slowly.
- Monitor for postural BP.
Controversies in Care: Glycemic control
Several large prospective randomized trials have been published that have raised questions about appropriate targets and interventions for glycemic control for sub-populations of people with diabetes.
In support of A1C reduction and clinical complication reduction:
- The DCCT Trial showed that intervention with insulin for a mean of 6.5 years in people with type 1 diabetes to lower A1C (7.3% vs. 9.1%) resulted in reduced retinopathy progression, proteinuria progression, and neuropathy progression.15 A ten-year follow-up study also showed a "legacy" effect of that earlier period of intervention with reduced cardiovascular disease, myocardial infarction and death.16
- The UKPDS showed that intervention with metformin, sulfonylureas and/or insulin in patients with newly diagnosed type 2 diabetes for a median follow-up of ten years to lower A1C (7.0% vs. 7.9%) resulted in reduced microvascular disease (largely driven by reduced need for retinal photocoagulation).17 In particular metformin is uniquely effective in decreasing macrovascular outcomes. A ten-year follow-up study also showed a "legacy" effect of that earlier period of intervention with reduced microvascular disease, myocardial infarction and death from any cause.18
- A recent meta-analysis appears to show that "more-intensive glycemic control affords a modest but significant cardiovascular benefit in the short-to-medium term…"19
Studies with A1C reduction showing either no benefit for complication reduction or harm:
- The VADT trial enrolled 1791 US veterans with type 2 diabetes. Coronary artery disease prevalence was 40%. Glycemic targets were A1C <6.0% vs. <9.0% for insulin addition. Achieved A1C was 7.0% vs. 8.5%. Metformin, glimepride and rosiglitazone were oral agents. There was no difference in cardiovascular outcomes or death rate in the two groups and there was significantly higher rate of hypoglycemia in the intensive group.20
- The ACCORD study glycemic control arm examined a population of 10,251 people with type 2 diabetes at increased risk for cardiovascular complications on the basis of existing cardiovascular disease or risk factors. All patients received blood pressure and lipid lowering therapy. The glycemic targets were A1C <6.0% (intensive-therapy group) vs. 7.0-7.9% (standard-therapy group). Multiple agents were used to achieve the targets, with 77% of the intensive-therapy group receiving insulin and the majority of this group also using at least 3 classes of oral agents. The intensive-therapy group was terminated because of a statistically significant excess mortality compared to the standard-therapy group.21
The 2008 CDA Guidelines use a "single A1C target" of ≤7.0% to make it "easier to incorporate into clinical practice" but acknowledge that "clinical judgment is required to determine which people can reasonably and safely achieve these targets".22 A1C lowering in type 1 DM and newly diagnosed type 2 DM is associated with reduced complications; however, in patients with existing or high risk for CVD there is no evidence that a stringent A1C (less than 6) has a benefit and there are increased side effects.
Controversies in Care: Risk Calculation
Some authorities suggest all patients with diabetes should be considered at high risk (20% ten year risk for a CAD event or 2% per year) for coronary artery disease.23 This recommendation is often based on an article by Haffner et al. which showed equal risk for death from coronary artery disease in a cohort of diabetic patients who had not had an MI and of non-diabetic patients who had a previous MI.24 But a recent meta-analysis by Bulugahapityia et al., which included the Haffner data, demonstrated significantly lower risk of CAD for patients with diabetes compared to those with a prior MI.25
Recent CDA guidelines recommended that all men with diabetes over age 45 and all women with diabetes over age 50 (and some under those age cut-offs) be considered at high risk for CAD.26 This recommendation was based on an article by Booth et al. Booth demonstrated that the average man with diabetes in a cohort (Ontario, Canada) became high risk at the age of 49 and the average woman with diabetes at age 56.27
The alternative to such broad, population-based, definitions of "high risk" is an individual calculation using a risk calculator (e.g., UKPDS risk calculator and DiabetesPHD (personal health decisions). Many other risk calculators also exist. Risk calculators differ in terms of ease of use and data entered. They may over- or under-estimate a patient's true risk. But, risk calculators provide the clinician the ability to input a variety of patient specific characteristics (more than just age and gender) in order to estimate a patient's risk for a variety of diabetes-related complications.
Controversies in Care: SMBG
SMBG is a commonly recommended medical technology. On a population basis, the majority of glucose test strip use is by people with type 2 diabetes who do not use insulin. A recent meta-analysis of this group showed a slightly lower A1C (-0.25%) in patients who perform SMBG vs no testing.28 The review found "sparse and inconsistent data" to suggest that SMBG conferred benefit in terms of Health-Related Quality of Life, patient satisfaction, long-term complications and mortality. When economic factors were also reviewed, SMBG was found to be relatively cost-ineffective and routine self-testing of blood glucose was not recommended in this population. The review suggested that the frequency of SMBG be "individualized" in certain groups of people, e.g patients with diabetes who use insulin, patients with gestational diabetes, or those who have special considerations i.e adjustment of medication regimen.29
Controversies in Care: Lipid Targets
The issue of lipid targets for patients with diabetes is complicated and often debated in the context of CV risk assessment and clinical trial results. There are several algorithms for the CV risk: UKPDS, Framingham, Procam, Reynold etc. Depending on which one is used, the predicted risk may be remarkably different. The results from prospective, double blind, placebo-controlled statin trials in patients with diabetes show significant benefits of the treatment. Thus the current expert opinion from the Canadian Cardiovascular Society (CCS) and American Diabetes Association (ADA) guidelines state that "most patients with diabetes will benefit from treatment with statins to the high risk LDL-C or ApoB target".30,31 It is hoped that these numbers guide treatment rather than define an absolute target that must be achieved.
- Canadian Diabetes Association Clinical Practice Guidelines Expert Committee. Prevention of Diabetes. Can J Diabetes. 2008;32 (Supp.1):S17-S19.
- Chiasson JL, Rabasa-Lhoret R. Prevention of type 2 diabetes insulin resistance and β-cell function. Diabetes. 2004;53(S3):S34-S38.
- Lindstrom J, IIane-Parikka P, Aunola S, et al. Sustained reduction in the incidence of type 2 diabetes by lifestyle intervention: follow-up of the Finnish Diabetes Prevention Study. Lancet. 2006;368:1674-69.
- Canadian Diabetes Association Clinical Practice Guidelines Expert Committee. Screening for type 1 and type 2 diabetes. Can J Diabetes. 2008;32(Supp.1):S14-S16.
- International Expert Committee. International Expert Committee report on the role of the A1C assay in the diagnosis of diabetes. Diabetes Care. 2009;32:1327-1334.
- Canadian Diabetes Association Clinical Practice Guidelines Expert Committee. Management of obesity in diabetes. Can J Diabetes. 2008;32(Supp.1):S77-S81.
- Canadian Hypertension Education Program. 2010 CHEP recommendations for the management of hypertension. 2007. www.hypertension.ca/chep/
- Nathan DM, Zinman B, Cleary PA. Diabetes control and complications trial/epidemiology of diabetes interventions and complications (DCCT/EDIC) research group. Modern-day clinical course of type 1 diabetes mellitus after 30 years' duration. Arch Intern Med. 2009;169(14):1307-1316.
- Chalmers J, Cooper ME. UKPDS and the legacy effect. N Engl J Med. 2008;395(15)5:1618-1620.
- Genest J, McPherson R, Frohlich, J. et al. 2009 Canadian Cardiovascular Society/Canadian guidelines for the diagnosis and treatment of dyslipidemia and prevention of cardiovascular disease in the adult - 2009 recommendations. CJC 2009;25:567-579.
- Canadian Diabetes Association Clinical Practice Guidelines Expert Committee. Management of obesity in diabetes. Can J Diabetes. 2008;32 (Supp.1):S105.
- The ONTARGET Investigators. Telmisartan, ramipril, or both in patients at risk for vascular events. N Engl J Med. 2008;385:15: 1547-1559.
- Canadian Diabetes Association Clinical Practice Guidelines Expert Committee. Prevention of diabetes. Can J Diabetes. 2008:32(Supp.1):S82.
- Ismail K, Winkley K, Rabe-Hesketh S. Systematic review and meta-analysis of randomized controlled trials of psychological interventions to improve glycemic control in patients with type 2 diabetes. Lancet. 2004;363:1589-1597.
- DCCT Research Group. The effect of intensive treatment of diabetes on the development and progression of long-term complications in insulin-dependent diabetes mellitus. N Engl J Med. 1993;329:977-86.
- The Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications (DCCT/EDIC) Study Research Group. N Engl J Med. 2005; 353:2643-2653.
- United Kingdom Prospective Diabetes Study Group (UKPDS). Intensive blood glucose control with sulphonylureas or insulin compared with conventional treatment and risk of complications in patients with Type 2 diabetes. Lancet. 1998;352:837-53.
- The Advance Collaborative Group. Intensive blood glucose control and vascular outcomes in patients with type 2 diabetes. N Engl J Med. 2008;358:2560-2572.
- Turnbull FM, Abraira C, Anderson RJ. Intensive glucose control and macrovascular outcomes in type 2 diabetes. Diabetologia. 2009 Nov;52(11):2288-98.
- Duckworth W, Abraira C, Moritz T, et al. Glucose control and vascular complications in Veterans with type 2 diabetes. N Engl J Med. 2009;360:129-39
- The Action to Control Cardiovascular Risk in Diabetes Study Group. Effects of intensive glucose lowering in type 2 diabetes. N Engl J Med. 2008;358:2545-2559.
- Canadian Diabetes Association Clinical Practice Guidelines Expert Committee. Canadian Diabetes Association 2008 Clinical Practice Guidelines for the Prevention and Management of Diabetes in Canada. Can J Diabetes. 2008;32(Suppl1) S30.
- McPherson R, Frolich J, Fodo G, et al. Canadian Cardiovascular Society position statement - recommendations for the diagnosis and treatment of dyslipidemia and prevention of cardiovascular disease. Can J Cardiol. 2006;22:913-27.
- Haffner SM, Lehto S, Ronnemaa R, et al. Mortality from coronary heart disease in subjects with type 2 diabetes and in non diabetic subjects with and without prior myocardial infarction. New Engl J Med. 1998;339:229-34.
- Bulugahapitiya U, Siyambalapitiya S, Sithole J, et al. Is diabetes a coronary risk equivalent? Systematic review and meta-analysis. Diabetic Medicine. 2009;16;142-148.
- Canadian Diabetes Association Clinical Practice Guidelines Expert Committee, Canadian Diabetes Association 2008 clinical practice guidelines for the prevention and management of diabetes in Canada. Can J Diabetes. 2008;32(suppl1):S95.
- Booth GL, Kapral MK, Fung K, et al. Relation between age and cardiovascular disease in men and women with diabetes compared with non-diabetic people: a population-based retrospective cohort study. Lancet. 368:29-36.
- Canadian Agency for Drugs and Technology in Health (CADTH). Optimal Therapy Recommendations for the Prescribing and Use of Blood Glucose Test Strips, Volume 3, Issue 6, July 2009.
- Cameron C, Coyle D, Ur E. et. al. Cost-effectiveness of self-monitoring of blood glucose in patients with type 2 diabetes mellitus managed without insulin. Can. Med. Assoc. J., Jan 2010; 182: 28 - 34
- Genest J, McPherson R, Frohlich J. et al. 2009 Canadian Cardiovascular Society/Canadian guidelines for the diagnosis and treatment of dyslipidemia and prevention of cardiovascular disease in the adult - 2009 recommendations. Can J Cardio. 2009; 25(10): 567-579.
- American Diabetes Association: Standards of Medical Care in Diabetes - 2009. Position statement. Diabetes Care. 2009; 32:(1) S13-S61.
- Douglas IJ, Evans SJ, Pocock S, et al. The Risk of fractures associated with thiazolidinediones: a self-controlled case-series study. PLoS Med. 2009;6(9):e1000154.
- Nathan DM, Buse MH, Davidson MB. Medical management of hyperglycemia in type 2 diabetes: A consensus algorithm for the initiation and adjustment of therapy. Diabetes Care. 2008; 32:193-203.
List of Abbreviations and Acronyms
|A1C||glycosylated hemoglobin, formerly known as HbA1C|
|ACEI||angiotensin-converting enzyme inhibitors|
|ARB||angiotensin II receptor blocker|
|BID||to be taken twice a day|
|BMI||body mass index|
|CHD||coronary heart disease|
|CHF||congestive heart failure|
|eCPS||Electronic Compendium of Pharmaceuticals and Specialties|
|CSII||continuous subcutaneous insulin infusions|
|eGFR||estimated glomerular filtration rate|
|FPG||fasting plasma glucose|
|HDL-C||high-density lipoprotein cholesterol|
|IFG||impaired fasting glucose|
|IGT||impaired glucose tolerance|
|LDL-C||low-density lipoprotein cholesterol|
|OD||to be taken once a day|
|OGTT||oral glucose tolerance test|
|SMBG||self-monitoring of blood glucose|
|TID||to be taken three times a day|
|UKPDS||United Kingdom Prospective Diabetes Study|
|ULN||upper limit of normal|
Appendix A: Screening Algorithm for Type 2 Diabetes in Adults
Appendix B: Management of Hyperglycemia in Type 2 Diabetes
Appendix C: Antidiabetic Agents and Adjunctive Agents for Use in Type 2 DM
Appendix D: Insulin Therapeutic Considerations and Availability
Appendix E: Treatment of Hypoglycemia
Diabetes Patient Care flow sheet
Patient Education and Resources
This guideline is based on scientific evidence current as of the Effective Date.
The guideline was developed by the Guidelines and Protocols Advisory Committee, approved by the British Columbia Medical Association and adopted by the Medical Services Commision.
The principles of the Guidelines and Protocols Advisory Committee are to:
- encourage appropriate responses to common medical situations
- recommend actions that are sufficient and efficient, neither excessive nor deficient
- permit exceptions when justified by clinical circumstances.
Disclaimer The Clinical Practice Guidelines (the "Guidelines") have been developed by the Guidelines and Protocols Advisory Committee on behalf of the Medical Services Commission. The Guidelines are intended to give an understanding of a clinical problem and outline one or more preferred approaches to the investigation and management of the problem. The Guidelines are not intended as a substitute for the advice or professional judgment of a health care professional, nor are they intended to be the only approach to the management of clinical problems. We cannot respond to patients or patient advocates requesting advice on issues related to medical conditions. If you need medical advice, please contact a health care professional.