last authored: Sept 2013, David LaPierre
last reviewed:
Diabetes is a major health concern, affecting up to 10% of Canadians and leading to a two-fold risk of premature death. There are up to 60,000 new cases of diabetes in Canada each year, and between 80-90% of people with diabetes mellitus have T2DM. Though numbers are likely now drastically higher, in 2006, over 230 million people had diabetes - almost 6% of the world's adult population - and over 3 million die of it yearly (World Diabetes Foundation, 2006). India appears to have the highest rates.
Diabetes is expensive. In 2010, it accounted for 11.6% of total gobal healthcare expenditures (International Diabetes Federation).
Comorbidities can cause major challenges.
People with Type II diabetes are frequently obese and are often over 40, though it is being increasingly seen in children and adolescents.
Patients with type II diabetes have a combination of insulin resistance and dysfunctional beta cells, though they do not require insulin. Metabolic changes are milder than in Type I, as levels of insulin secretion do restrict ketogenesis and ketoacidosis.
Risk factors include:
It is the leading cause of end-stage renal disease, adult-onset blindness, and nontraumatic leg amputations.
The prevalence of diabetes is increasing due to increased rates of obesity and inactivity. Rates of Type II diabetes in children are increasing at a disturbing rate. Recent data suggests an American child born in 2000 stands a one in three chance of being diagnosed with diabetes in his or her lifetime. (www.diabetes.ca)
For people born in the US in 2000, the risk of developing T2DM is 1/3 for males and 2/5 for females.
By 2030, chronic diseases will cause 75% of all deaths globally.
In 2010, there were an estimated 286million people with diabetes (refs).
The simultaneous explosion of diabetes and obesity has led to the term diabesity.
Disease of affluence, and the rapidly growing middle class in developing countries
In NS, 1/11 people. Up 20% in past 5 years. 500 new cases/month.
By age 75, approximately 20% of people have T2DM.
Up to half of people with diabetes are undiagnosed. Type II diabetes develops gradually, without symptoms, and most commonly, diagnosis is made after routine blood or urine testing.
Patients with diabetes can present with:
skin problems
Prediabetes (see below) describes a state of elevated blood glucose levels remaining below those of T2DM. It is best diagnosed with the glucose tolerance test, but can also be done using FPG.
In Canada, fasting blood glucose should be tested in everyone >40 every 3 years, or more frequently in people with any risk factors. Mass screening for T2DM is not recommended.
Urinalysis - glucose, ketones, protein
Children should be screened if they are >10 (or puberty) every 2 years using FPG if they have >1 risk factors:
Diabetes mellitus may be diagnosed in various ways:
one instance of:
two of the following:
OGTT: pancreatic stress test
Note: HbA1c can be skewed by recent blood transfusions.
Prediabetes is diagnosed with the following values:
Impaired fasting glucose (IFG):
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Impaired glucose tolerance (IGT):
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Prediabetes: A1c 6.1-6.4%
Ketoacidosis is uncommon, presumably due to levels of portal vein insulin levels and sufficient fatty acid oxidation.
Hyperosmolar nonketotic coma can result from severe dehydration.
Type II DM is characterized by hyperglycemia, caused by insulin resistance, or a decreased ability of peripheral tissues to respond to insulin, as well as beta cell dysfunction, leading to impaired insulin secretion.
There is a strong genetic predisposition is behind many cases of type II DM. Among identical twins, concordance rates are 50-90%, and the risk of developing the disease is 20-40% (cf 5-7%) with one first-degree relative with T2DM. No more than 1-5% of patients have a point mutation in the insulin receptor, and beyond this the genetic basis of insulin resistance remains enigmatic. Polymorphisms with subtle effects are likely.
Insulin resistance is the decreased ability of target tissues - muscle, adipose tissue, and liver - to properly respond to circulating insulin. The liver produces excessive glucose, and muscle and adipose tissue decrease their glucose uptake. It can be measured 10-20 years before the onset of T2DM, and is one of the best predictors of progression.
Obesity is the most common cause of insulin resistance, although most obese patients with insulin resistance do not become diabetic. Individuals can compensate with increased insulin levels - insulin can be 2-3x higher in obese individuals. This keeps blood glucose levels within the normal range.
Mechanisms of insulin resistance include:
Insulin resistance increases with weight gain and decreases with weight loss, suggesting that fat accumulation is important. Adipose hormones such as leptin, resistin, and adiponectin all may contribute to insulin resistance, as may increased levels of FFAs.
Type II diabetes can develop following insulin resistance in people who also have beta cell dysfunction. The elderly, the obese, and pregnant women are often unable to compensate for insulin resistance with increased insulin production, and over time beta cells may die, resulting in hyperglycemia.
Prediabetes [impaired plasma glucose (IPG) or impaired glucose tolerance (IGT)] occurs with fasting glucose between 110-126, or GTT between 140-200.
Beta cells hypertrophy to secrete increased levels of insulin, attempting to maintain normal glucose levels. This is accompanied by reduced insulin activity in the liver, adipose tissue, and muscles. Declining beta cell function and increasing hepatic glucose production leads to overt diabetes, with fasting and postprandial hyperglycemia. Beta cell burnout results in 5-10% of people with prediabetes advanceing to DM each year.
Although insulin levels can vary among Type II diabetes patients, in all cases there is not enough insulin to correct hyperglycemia. As the disease progresses, there is a declining ability to control hyperglycemia. This may contribute to the demise of beta cells.
During initial states of insulin resistance, insulin secretion increases via cellular hypertrophy. This can maintain normal plasma glucose for years. Over time, however, insulin levels fall as beta cells die and decrease in their secretory ability. Both lipotoxicity (from increased FFAs) or glucotoxicity may be behind this.
Hormone-replacement therapy is eventually necessary.
Tonic hyperglycemia occurs due to a lack of uptake, as well as an increase in glycogenolysis and gluconeogenesis.
Hyperglycemia results from increased liver production of glucose and decreased peripheral uptake.
Ketosis is usually minimal or absent because of the presence of insulin.
Lipoprotein degradation by lipoprotein lipase in adipose tissue is decreased in diabetes, resulitng in increased plasma levels of chylomicrons and VLDLs and therefore hypertriacylglycerolemia.
Studies have shown most of the complications of diabetes are due to hyperglycemia, with genetic components leading to predisposition. Both duration and magnitude of sustained hyperglycemia (as measured by HbA1C) and also the fluctuations in blood levels contribute to damage. At least four distinct pathways are involved:
Advanced Glycation End Products (AGEs) cause a number of problems:
Protein Kinase C, signalling through DAG induces many genes, including VEGF, eNOS, TGF-beta, PAI-1.
The hexosamine pathway flux increases TGF-b1 and PAI-1, both of which are bad for blood vessels.
Ipolyol pathway flux decreases levels of NADPH, leading to low levels of reduced glutathione (GSH), an important antioxidant.
Diabetes is a progressive disease, over 7-10 years. Complications tend to appear 15-20 years after onset of hyperglycemia. Risk increases 2x in males and 3-4x in females, equalling the risk.
Acute complications include
Insulin resistance goes up during stress/illness.
Macrovascular disease results from problems with large- and medium-sized muscluar arteries, and causes accelerated atherosclerosis in people with diabetes. This can lead to increased risk for myocardial infarction, stroke, and gangrene inthe legs. MI is the most common cause of death in people with diabetes.
Biggest risk factor is age. Canadian guidelines suggest a 45 year-old man should be viewed as a 60 year-old when it comes to cardiovascular risk. In younger patients, risk for CAD is assessed based on other risk factors.
Up to 1/3 of MIs can be silent, occurring without recognized or typical symptoms.
Macrovascular disease appears meadiated primarily by increased levels of free fatty acids (FFAs), not hyperglycemia. Because of this, tight blood glucose control alone will not prevent the big guns, and lipid lowering agents need to be added.
Diabetes can also lead to hypertension, dyslipidemia, and platelet dysfunction.
Microvascular disease is caused by problems in capillary dysfunction in target organs unable to regulate a response to hyperglycemia, including endothelial cells (particularly those in the retina), mesangial cells in the kidney, and neurons and Schwann cells in peripheral nerves. Effects of tonic hyperglycemia thus include diabetic retinopathy, nephropathy, and neuropathy. The vasculature is affected by hypertension, dyslipidemia, inflammation, and impaired fibrinolysis
Microangiopathy involves thickening of the basement membranes, especially in the capillaries of the skin, muscle, retina, renal medulla, and glomeruli.
Diabetic nephropathy
Diabetic nephropathy (protein >300mg/day) is the most important cause of end-stage renal disease in the US and can lead to nephrotic syndrome.
It occurs due to glomerular lesions, renal vascular lesions, and pyelonephritis. Up to 30-40% of people with type I and about 20% of people with type II diabetes develop nephropathy, which is greatly influenced by genetics (Native Americans, blacks, and Hispanics have a greater risk).
Microalbuminuria is an early marker, almost inevitably to overt nephropathy within 5 years. It is associated with increased cardiovascular mortality.
Diffuse glomerulosclerosis is the most common lesion, with a uniform increase in mesangial matrix. Hyaline arteriosclerosis can affect afferent and efferent arterioles.
Leading cause of end-stage renal disease in Canada
Ocular involvment can include retinopathy, cataract formation, or glaucoma. Within 15-20 years of diagnosis, 60-80% of people with diabetes have some form of diabetic retinopathy, with neovascularization (probably attributable to VEGF) being very important.
Diabetic neuropathy clinically affects up to 50% of patients who have lived with DM for over 25 years. Neuropathies can be sensory, sensorimotor, or autonomic. Axonal neuropathy is prominent, with relative loss of small fibres. Arterioles are affected. It is not clear if ischemia or metabolic problems are most causative.
Symmetric peripheral neuropathies are the most common. Mononeuropathies involving a single peripheral or cranial nerve are possible, as are multiple mononeuropathies.
Neuropathic ulcers cause huge problems for people with diabetes.
Gastroperesis, sexual dysfunction
Erectile dysfunction
Approximately 30% of patients with diabetes mellitus develop a skin disorder sometime during the course of disease.
Foot ulcers
Intertrigo: Dermatitis (inflammation) soccurring between folds or juxtaposed surfaces of the skin and caused by sweat retention, moisture, warmth, and the overgrowth of resident microorganisms.
Onychomycosis: A fungal infection of the fingernails or toenails that results in thickening, flaking, roughness, and splitting of the nails. Usually caused by Trichophyton rubrum or T. mentagrophytes. Aka: tinea unguium.
Mycosis: A contagious fungal skin infection caused by a species of Trichophyton or Epidermophyton that usually affects the feet, especially the skin between the toes, and is characterized by itching, blisters, cracking, and scaling (aka Also called tinea pedis.)
Xanthoma: A benign lesion composed of lipid laden foam cells, which are histiocytes containing cytoplasmic lipid material.
Xanthelasma: Same as above, except usually sharply demarcated yellowish collection of cholesterol underneath the skin on or around the eyelids (above & below inner canthus)
Shin Spots (Diabetic Dermopathy or pigmented pretibial patches): These are found in other conditions, but are the most common cutaneous finding in diabetes. Characterized by bilateral multiple hyperpigmented macules on the pretibial areas. Due to the frequent location of the lesions over bony prominences, diabetic dermopathy may simply be a magnified response to trauma. In several studies, shin spots were produced in response to trauma with heat, cold, or blunt objects in persons with diabetes. Lesions may also appear on the forearm, the side of the foot, and the anterior surface of the lower thigh. Lesions are round or oval, reddish-brown, scaly papules and plaques, of various sizes. The lesions eventually evolve into the characteristic shallow pigmented scars typical of diabetic dermopathy.
Diabetic bullae
Granuloma annulare
Acanthosis nigricans (AN)
Ketoacidosis results from periods of increased adipocyte breakdown of fatty acids and hepatic conversion of fatty acids acetylCoA into ketone bodies for use as fuel by tissues such as brain, heart, and muscle.
Diabetes in adults is associated with a high risk of vascular disease (2- to 4-fold greater than that of individuals without diabetes), with CVD the primary cause of death among people with type 1 or type 2 diabetes. Aggressive management of all CV risk factors, including dyslipidemia, is therefore generally necessary. The most common lipid pattern in type 2 diabetes consists of hypertriglyceridemia (hyper-TG), low high-density lipoprotein cholesterol (HDL-C) and normal plasma concentrations of low-density lipoprotein cholesterol (LDL-C). However, in the presence of even mild hyper-TG, LDL-C particles are typically small and dense and may be more susceptible to oxidation. Chronic hyperglycemia promotes the glycation of LDL-C and both these processes are believed to increase the atherogenicity of LDL-C. In those with type 1 diabetes, plasma lipid and lipoprotein concentrations may be normal, but there may be oxidation and glycation of the lipoproteins, which may impair their function and/or enhance their atherogenicity.
Increased Atherosclerosis:
Diabetes can increase the risk of preinatal depression (Kozhimannil et al, 2009).
Anxiety in 40%
Depression in 15%
Diabetic osteopathy can be caused by bone demineralization and resorption.
Higher post-op mortality (increased infection, CV events).
A patient's ability to achieve target is affected by:
|
fasting/preprandial |
2h post-prandial |
HbA1c |
blood pressure |
lipids (mmol/L) |
healthy levels |
4-6 |
5-8
|
<0.06 |
< 130/80 |
LDL: <2.0 TG: <1.5 ratio: <4.0 |
recommended |
4-7 |
5-10 |
<0.07 |
|
|
suboptimal |
7.1-10.0 |
|
0.07-0.084 |
|
|
inadequate |
>10.0 |
|
>0.084 |
|
|
in-hospital |
no definite guidelines: 5-11 a rule of thumb |
|
>0.084 |
|
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Tight control early on - within the first five years, appears to be quite important. However, intensive glucose lowering appears not to positively impact mortality, and does increase risk of severe hypoglycemia (Boussageon et al, 2011).
Some patients should have a target of 7-8.5%. These include:
Frequent checks do not appear to benefit patients, especially frail older people. Once daily checks are sufficient.
1-2/day at different times (ac and pc meals); more often on insulin.
Self-monitoring blood glucose (SMBG) provides instant snapshots of blood glucose.
It is associated with healthy eating, weight loss, and achieving blood glucose goals.
Two-hour post-prandial testing is a better predictor of CVD and all-cause mortality. This association is linear. The closer A1C is to 7.0%, the more of an influence post-prandial glucose plays.
Pattern management:
Fix one issue at a time: hypoglycemia first, fasting glucose next, and then postprandial hyperglycemia.
If you ask a patient to fill out a record, ensure you also ask to see it at next visit. It will be
When blood sugars are off topic, consider:
Kidney function should be screened with the following tests and frequency:
Chronic kidney disease is diagnosed with an ACR of >2 mg/mmol, and/or an eGFR of <60 ml/min
Screening should be carried out
Screening should be done with monfilament and a tuning fork.
While hospital-based services and internal medicine specialists used to be responsible for diabetes management, primary care professionals - family physicians, nurses, dietitians, etc - are increasingly providing diabetes care.
There are three main themes of management: treat short term concerns, equip patients psychologically, and prevent long term complications. Management should span 5 main areas: A1C, systolic blood pressure, LDL levels, ASA, and not smoking.
Initial management should be centred on lifestyle modifications, along with referral to a diabetes education program if possible.
Kidney-damaging medications to be held
if patient is unwell/dehydrated (SADMAN):
Gillies et al, 2007 published a meta-analysis showing that lifestyle interventions appear at least as effective as treatment with glitzazones in preventing type II diabetes, with both reducing progression of glucose intolerance by 50% or more. The authors warn of turning healthy people into patients unnecessarily.
This entails adopting healthy eating habits, achieving and maintaining a healthy weight, engaging in regular physical activity and smoking cessation.
Lifestyle should be the first treatment, unless A1C is 9% or higher. If targets are not reached within 2-3 months, medications should be strongly considered.
Lifestyle is incredibly difficult, as it requires total lifestyle change, predominantly of the family.
Lifestyle intervention continues to be protective against diabetes after studies have ended, as Lindstrom et al, 2006 found.
People sually eat what they like to eat, and are used to eating.
Use blood glucose to provide feedback to patients re: what their meals are doing to them.
A 5-10% reduction in weight has significant improvement in diabetes control.
Quitting smoking.
Bariatric surgery increases incretins for up to 20 years
someone said it can resolve diabetes in over 80% of people.
Medications should be used to reach target A1C levels within 6-12 months.
Oral hypoglycemics are the initial mainstay for managing TII DM.
Metformin is the first-line agent for use used if blood glucose levels are not restored by diet and exercise in 2-4 months. If patients' initial A1C is above 9%, combination therapy or insulin should be considered as initial treatment.
Second-line -A lengthy list of agents can be selected according to specific patient situation. This includes any of the oral hypoglycemics, as well as insulin.
Guidelines include:
In seniors, the biggest risk is low blood sugar. Metformin is the ideal choice. Insulin should be avoided, especially in sliding scales. Aim for 6-14.
Complicating factors include:
The following medications should be held when patients are sick and become dehydrated
A number of elements should be present to assist with vascular protection, and the number of medications taken usually increases with duration of disease.
ACE inhibitors or angiotensin receptor blockers (ARBs) are very useful for blood pressure control and to reduce levels of proteinuria. The medications that have been shown to be protective include ramipril, perindopril, and telmasartan.
However, most patients will require multiple drugs for adequate blood pressure control.
Current targets are for a BP of <130/80, though there is increasing evidence that this tight control does not result in improved outcomes.
ACEi and ARBs should be used in all patients with:
Note: these drugs should not be used if pregnancy is present, or is being considered, given the teratogenic effects they can have.
Statins should be used in the following groups:
Note: statins should not be used if pregnancy is present, or is being considered, given the teratogenic effects they can have.
Adults at high risk of vascular disease should be treated with a statin to achieve an LDL-C ≤2.0 mmol/L. Clinical judgement should be used as to whether additional LDL-C lowering is required for adults with an on-treatment LDL-C of 2.0 to 2.5 mmol/L. The primary target is LDL, and the secondary is ratio.
If the TC/HDL-C ratio is ≥4.0, consider strategies to achieve a TC/HDL-C ratio <4.0, such as improved glycemic control, intensification of lifestyle (weight loss, physical activity, smoking cessation) and, if necessary, pharmacologic interventions.
In adults with serum TG >10.0 mmol/L despite best efforts at optimal glycemic control and other lifestyle interventions (e.g. weight loss, restriction of refined carbohydrates and alcohol), a fibrate should be prescribed to reduce the risk of pancreatitis.
For those with moderate hyper-TG (4.5 to 10.0 mmol/L), either a statin or a fibrate can be attempted as first-line therapy, with the addition of a second lipid-lowering agent of a different class if target lipid levels are not achieved after 4 to 6 months on monotherapy.
For adult patients not at target(s), despite optimally dosed first-line therapy as described above, combination therapy can be considered. Options include:
Anticoagulation, with ASA or clopidogrel, should be used when macrovascular disease is present.
There are many treatments that are used for neuropathy (main article)
Retinopathy can be slowed through good sugar control, as well as the addition of fibrates.
Opthalmologic treatments can include laser photocoagulation, intra-ocular injections, or retinal surgery
There are a number of points that should be made to patients (CDA, 2013):
Do
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Do Not:
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Impaired glucose tolerance (IGT) diagnosis is a critical period to offer lifestyle support.
Medications, especially metformin, can prevent progression.
According to some, the majority of failure to meet management goals is due to improper scheduling of patient visits and follow-up.
Ontario data show over 92% of diabetes care is provided by family doctors, alone or in combination with a specialist (Ontario Diabetes Database). Primary care plays many important roles:
Primary care networks or family health teams involve nurses and dietitians.
While much care is provided by primary care, specialists have a role to play for complex patients. Communication with primary caregivers is critical.
Diabetic patients have twice the visits to family physicians in Canada.
In adults, fasting lipid levels (TC, HDL-C, TG and calculated LDL-C) should be measured at the time of diagnosis of diabetes and then every 1 to 3 years as clinically indicated. More frequent testing should be performed if treatment for dyslipidemia is initiated.
Yearly eye exams,
Regular foot exams.
A. Fagot-Campagna, D.J. Pettitt and M.M. Engelgau et al., Type 2 diabetes among North American children and adolescents: an epidemiologic review and a public health perspective, J Pediatr 136 (2000), pp. 664–672
Boussageon R et al. 2011. Effect of intensive glucose lowering treatment on all cause mortality, cardiovascular death, and microvascular events in type 2 diabetes: meta-analysis of randomised controlled trials. BMJ. 343.
Knowler WC, et al. 2002. Diabetes Prevention Program Research Group. Reduction in the incidence of type 2 diabetes
with lifestyle intervention or metformin. N Engl J Med 346(6):393-403.
Kozhimannil KB, Pereira MA, Harlow BL. 2009. Association between diabetes and perinatal depression among low-income mothers. JAMA. 301(8):842-847.
Ontario Diabetes Database, Ontario Health Insurance, 1999-2000.
Canadian Diabetes Association Clinical Practice Guidelines
UKPDS - intensive blood sugar and HT lowering decreased microvascular complications, but not macrovascular.