Type 2 diabetes and impaired fasting glucose and metabolic syndrome, which presage diabetes, are becoming increasingly common among Canadian adults. As is well known, chronically elevated blood glucose engenders a wide range of deleterious effects on various body tissues and systems. Cardiovascular disease (CVD) is the leading cause of death in people with diabetes and occurs two to four times more often than in people without diabetes. Diabetes is the leading cause of blindness, end-stage renal failure (ESRD), and non-traumatic amputation in Canadian adults. People with diabetes are also far more likely to be hospitalized for cardiovascular disease, kidney disease, and amputation than the general population. Depression and anxiety are more common in people with diabetes than people without diabetes.
Prevention or postponement of the onset of type 2 diabetes through management of modifiable risk factors and appropriate early management of patients with prediabetic conditions may help lessen the expected epidemic of diabetes in Canada. Moreover, current evidence supports an aggressive approach to identifying and treating people with metabolic syndrome, with the aim of reducing morbidity and mortality from CVD. Lifestyle measures are crucial, and pharmacologic interventions are often necessary in patients at risk. In patients who have already developed diabetes, early recognition and optimized management can help prevent serious microvascular and macrovascular complications and premature death.
The clinical practice guidelines developed by the Canadian Diabetes Association are intended to disseminate current knowledge on the many aspects of diabetes care and prevention. They provide, in a structured format, the abundant evidence collected in epidemiological and clinical research since 2008, when the previous recommendations were issued.
All patients seen in primary care settings should undergo evaluation of their risk for type 2 diabetes, based on demographic and clinical criteria (Table 1). Screening using a fasting plasma glucose (FPG) and/or glycated hemoglobin (A1C) should be performed every 3 years in individuals ≥40 years of age. Clinicians may consider more frequent and/or earlier testing with either FPG and/or A1C or 2-hour plasma glucose (2hPG) in a 75-g oral glucose tolerance test (OGTT) in people with known risk factors.
The diagnosis of diabetes is made using any of the following criteria:
The term "prediabetes" refers to impaired fasting glucose (IFG), impaired glucose tolerance (IGT) or an A1C between 6.0 and 6.4%. People with prediabetes are at risk of developing diabetes and its complications (Table 2), although not all people with prediabetes will progress to diabetes.
It is important to identify individuals with prediabetes in order to implement strategies to prevent diabetes and modify CVD risk factors. It is possible to reduce the risk of, or delay the onset of, type 2 diabetes and decrease the likelihood of long-term complications with the following:
The overall aim of management is to minimize the risks of macrovascular and microvascular complications by achieving prescribed targets for blood glucose, blood pressure (BP), and lipids. Regular office or clinic visits to screen for complications and to ensure aggressive management of risk factors are integral parts of diabetes management. Table 3 indicates the recommended intervals for surveillance. The following sections provide additional details on the principles of care and follow-up.
Successful implementation of the treatment plan requires an integrated, cooperative approach by the physician, patient, and other members of a diabetes health care team. Typically, patients require ongoing education and support to ensure continued motivation and proficiency in self-management. While most patients can be managed satisfactorily in the primary care setting, the involvement of an endocrinologist or other specialist should be considered for patients whose condition is more difficult to manage.
Actively encouraging a healthy lifestyle in overweight and obese people with diabetes can help them to achieve and maintain a healthy body weight. The loss of between 5 and 10% of initial body weight can substantially improve insulin sensitivity, as well as glycemic, BP, and lipid control. The optimal rate of weight loss is 1–2 kg/month. A negative energy balance of 500 kcal/day is typically required to achieve a weight loss of about 0.45 kg per week.
Health behaviour interventions that combine dietary modification, increased and regular physical activity, and behaviour therapy are most effective. Structured interdisciplinary programs have shown better results.
Patients with diabetes should receive nutritional counselling on appropriate serving sizes and macro- and micronutrient intake.
In any individual with diabetes without contraindications, the goal for physical activity should be at least 150 minutes per week of moderate to vigorous aerobic exercise (e.g., brisk walking or swimming). The activity should take place on at least 3 days per week; there should be no more than 2 consecutive exercise-free days. Patients who have been sedentary may need to develop exercise tolerance gradually, starting with 5 to 10 minutes of walking daily. Regular resistance exercise (weight training) should also performed 2–3 times per week.
Pharmacotherapy (orlistat) may be used as an adjunct to health behaviour interventions.
Adults with type 2 diabetes and class II or III obesity (body mass index≥35.0 kg/m2) may be considered for bariatric surgery when other lifestyle interventions are inadequate in achieving weight management goals.
For most individuals, appropriate management of diabetes requires control of blood glucose aimed at achieving A1C≤7.0%; Table 4 shows associated fasting and postprandial glucose targets needed to achieve the target A1C. The A1C target may be less stringent for patients who have a high level of functional dependency or in whom age and/or comorbid conditions are associated with a limited life expectancy. A target of ≤6.5% may be considered in some patients to further lower the risk of nephropathy, but this must be balanced against the risk of hypoglycemia.
Patients with baseline A1C < 8.5% may attempt a trial of lifestyle measures plus metformin to control their blood glucose. However, if glycemic targets are not met within 2 to 3 months, further antihyperglycemic medication should be initiated and sustained as shown in Figure 1.
Metformin is the initial therapy for all patients. The clinician should adjust or add medication(s) so that the A1C target is met within 3 to 6 months of the start of pharmacotherapy. Tailoring of treatment may take into account such factors as the patient's degree of hyperglycemia, risk of hypoglycemia, overweight/obesity, the presence of diabetes complications or comorbidities, patient preference, and agent characteristics such as effectiveness in lowering blood glucose, side effects and contraindications, (e.g., as regards type of administration, cost and drug plan coverage, eating habits, weight gain, etc.) (Table 5).
The patient should perform self-monitoring of blood glucose at appropriate intervals (see full guidelines and "Self-Monitoring of Blood Glucose [SMBG] Recommendation Tool for Health care Providers"*).
The results on the home meter should be compared with a laboratory measurement of simultaneous venous FPG at least once per year or when indicators of glycemic control do not match the meter readings.
For most individuals with diabetes, A1C should be measured every 3 months to ensure that glycemic goals are being met or maintained. Longer intervals (e.g., 6 months) may be considered in stable patients who have consistently achieved the prescribed targets. The patient's experience with hypoglycemia (symptoms, possible cause, severity, frequency) should be reviewed at each visit.
Many patients with diabetes, with the possible exception of young and otherwise healthy individuals, should immediately be deemed at high cardiovascular (CV) risk. The risk of a premature CV event is most marked in those with traditional risk factors, such as smoking, hypertension, and dyslipidemia; those with features of metabolic syndrome; and those who have had diabetes for at least 15 years, hyperglycemia, and/or microvascular complications.
Given the relatively high likelihood of CVD morbidity and mortality in individuals with diabetes, a CV risk assessment should be performed promptly upon diagnosis. Additional tests should include a baseline resting electrocardiogram (ECG) in all individuals aged ≥40; aged >30 and duration of diabetes >15 years; with endorgan damage; or with other risk factors (hypertension, proteinuria, reduced pulses, vascular bruits). ECG should be repeated at least every 2 years.
ECG stress testing may be performed in patients with cardiac symptoms (e.g., unexplained dyspnea, chest discomfort), resting abnormalities on ECG, abnormal ankle-brachial ratio suggesting peripheral arterial disease, carotid bruits, stroke or transient ischemic attack.
Patients with diabetes require a comprehensive approach to macrovascular protection that includes both lifestyle modifications to ensure good general health and pharmacologic measures to optimize control of blood glucose, BP, lipids, and vascular health.
Patients with diabetes should have their BP measured with every diabetesrelated office or clinic visit. The Canadian Hypertension Education Program (CHEP) indicates hypertension should be diagnosed and treated in any individual with diabetes and BP >130/80 mmHg. The aim is to ensure BP reaches and remains <130/80 mmHg. (Please see the Hypertension chapter of the full guidelines.)
Hypertension in patients with diabetes should be treated aggressively to reduce the risk of vascular complications. Lifestyle interventions, including physical activity and a healthy diet with reduced sodium and alcohol intake, should be part of the treatment plan. Most individuals with diabetes will require several antihypertensive agents. Table 6 summarizes the CHEP guidelines for patients with diabetes.
Control of lipids is an important component of vascular protection in individuals with diabetes. At the time of diagnosis, a baseline lipid profile should be established with fasting levels of total cholesterol, high- and low-density lipoprotein cholesterol (HDL-C, LDL-C), and triglycerides (TG). (Note that a fast of 8+ hours may be inappropriate for some individuals with diabetes, especially those using longacting insulin.) Measurements should be repeated approximately yearly, or more frequently (every 3–6 months) if dyslipidemia is detected and treatment started.
For patients with indications for lipid-lowering therapy (see Vascular Protection chapter of the full guidelines), treatment should be initiated with a statin to achieve an LDL-C of ≤2.0 mmol/L.
Individuals who do not achieve the recommended targets with these measures may require a combination of statin therapy and second-line agents.
Patients whose TG is >10.0 mmol/L despite reasonable glycemic control and other lifestyle interventions may receive treatment with a fibrate while also optimizing glycemic control and implementing lifestyle interventions (e.g., weight loss, dietary strategies and reduced alcohol intake).
Patients with diabetes who are at high CV risk also may benefit from administration of an angiotensin converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB), as well as antiplatelet therapy (acetylsalicylic acid or clopidogrel).
Renal disease, including advanced nephropathy, may already be present at the time of diagnosis of type 2 diabetes. Screening should be performed at diagnosis, and yearly thereafter. Chronic kidney disease (CKD) is present in patients with a random urine albumin to creatinine ratio (ACR) is >2.0 mg/mmol and/or an estimated glomerular filtration rate (eGFR) is ≤ 60 mL/min on at least 2 out of 3 samples over a 3 months period, regardless of kidney function.
All adults with diabetes and chronic kidney disease should receive a comprehensive, multifaceted approach to reduce cardiovascular risk, including an ACE inhibitor or ARB to delay progression of CKD.
Referral to a nephrologist or specialist with expertise in CKD may be necessary in the following situations:
Screening should be performed at diagnosis and, in patients with minimal or no retinopathy at baseline, should be repeated every 1–2 years by experienced professionals with appropriate examination equipment. As with other diabetic complications, optimal control of blood glucose, BP, and lipids can help prevent progression of disease. Patients whose sight is threatened should be assessed by a general ophthalmologist or retina specialist.
Screening for peripheral neuropathy—conducted by assessing the loss of sensitivity to a 10-g monofilament—should take place at the time of diagnosis and annually thereafter. Intensified glycemic control can prevent the onset and progression of neuropathy. Anticonvulsants, antidepressants, opioid analgesics, or topical nitrate spray may be used alone or in combination for relief of painful peripheral neuropathy.
Regular foot examinations decrease the risk of foot lesions and amputations. Examinations should be performed at least annually and more frequently in those at high risk. The assessment should include an evaluation of skin changes, structural abnormalities, skin temperature, and symptoms or signs of neuropathy, infection, ulcerations, or peripheral arterial disease. Patients should be advised on daily foot care, self-examination, and counselled to see a health care professional for management of ulcerations.
Erectile dysfunction (ED) affects about 1 in 3 men with diabetes, and may be an early marker of vascular disease. All adult men with diabetes should be regularly screened for ED with a sexual function history.
Phosphodiesterase type 5 inhibitors may be offered as first-line therapy to men with diabetes seeking treatment for ED if there are no contraindications to their use.
Symptoms of depression and anxiety are more common in people with diabetes than in people without diabetes. Depressive disorders may lead to inadequate selfcare, less optimal control of blood glucose, increased morbidity, and poorer quality of life. Clinicians should be on the lookout for psychological distress and screen for depression and anxiety by interview or with a standardized questionnaire.
Diabetes is a highly complex disease that involves numerous management steps and components that must be individualized according to–among other factors–the patient's clinical condition; his or her knowledge, motivation, and ability to act to reduce risk factors and perform self-care; and the availability of an integrated care team. Ideally, patients at risk for type 2 diabetes will be identified early, so that preventive strategies can be initiated.
Patients with cardiovascular disease risk factors, such as diabetes, hypertension, and dyslipidemia, are at significantly increased lifetime risk for macrovascular events such as stroke and myocardial infarction. Consequently, patients should have all of their risk factors treated to their risk appropriate treatment targets.
The C-CHANGE (Canadian Cardiovascular HArmonization of National Guidelines Endeavour) Collaboration suggests that all cardiovascular disease risk factors should be addressed. Ideally, all patients should be stratified with respect to the cardiovascular event risk and should be at or below all their cardiovascular disease risk factors treatment targets.
Without doubt, it may be easier to treat one cardiovascular disease risk factor to target in one patient versus another patient and not all patients will get below their treatment targets for all their risk factors. However, a concerted effort should be made to get most patients to or below most of their risk factors targets through a combination of heart healthy behaviours and pharmacological therapies. In reality, addressing all the cardiovascular disease risk factors present in any single patient and ensuring they are each treated, preferably to or below target, is likely to have a greater impact on patient outcomes than treating any single risk factor perfectly while the others remain untreated or significantly undertreated.
Please refer to the C-CHANGE section in this publication for additional information.
The preceding text is only a concise summary of the 2013 Canadian Diabetes Association guidelines. Readers are encouraged to consult the full document (available at www.diabetes.ca) for precise details on type 2 diabetes screening and management.