Type 2 Diabetes is a disorder of glucose metabolism resulting from a combination of insulin resistance, relative insulin deficiency and increased glucose production from the liver. Unlike type 1 diabetes it tends to be heavily influenced by lifestyle and body weight. Type 2 Diabetes is more common in adults, however there is a rise in the prevalence of type 2 Diabetes in children and adolescents due to a paralleled increase in prevalence of childhood obesity.
Most people who have type 2 Diabetes have a gradual onset of symptoms for weeks and sometimes months before they are diagnosed, in some people there may even be early signs of complications at the time of diagnosis. Because of this, screening for Diabetes in at risk populations is essential to prevent and even delay complications from diabetes (see below for screening).
Symptoms
Signs and symptoms of type 2 Diabetes include:
Classical symptoms:
Polyuria – Excessive and frequent urination, high sugar in the blood stream will cause water to be pulled out from cells and loss of water in urine follows a high concentration of sugar in urine.
Polydipsia – Due to water loss there is increased thirst and water intake to curb dehydration, however if water loss exceeds intake this may result in severe dehydration.
Weight loss – this results from excessive water loss and the body using alternative forms of fuel stored in fat and muscle cells.
Other symptoms:
Fatigue and tiredness – from decreased or absent metabolism of sugar sometimes coupled with dehydration from water loss.
Increased hunger – even though there is high sugar in the bloodstream, cells cannot metabolize it due to relative insulin deficiency and/or resistance and this leads to a state of energy deficiency and results in hunger.
Frequent/recurrent infections (especially fungal) – high blood sugar also affects the immune cells that help fight infections and this can result in susceptibility to infections and delayed wound healing.
Acanthosis Nigracans – Darkening of the skin with velvety appearance on the folds/creases of the armpits and neck (a sign of insulin resistance)
Blurry vision – when sugar is too high fluid may be pulled into the eye lens and affect its ability to focus images, this is usually reversible within a few weeks of normalizing blood sugar provided there is no other damage to the rest of the eye.
Diabetic Ketoacidosis – Although not a feature of type 2 Diabetes some people may present with ketoacidosis (see section on Type 1 Diabetes) due to a sudden inability of the pancreas to produce insulin when blood sugar is too high, often called Ketosis-prone Diabetes or Flatbush Diabetes (named after an area in Brooklyn where it was first identified).
Risk Factors of Type 2 Diabetes:
The pathogenesis of type 2 Diabetes is poorly understood and heterogeneous, both genetic and environmental factors affect secretion of insulin and its resistance at the cellular level. Major risk factors include:
Overweight/obesity – there is a positive correlation between increase in BMI and the risk of developing Diabetes and this is due to the increase in insulin resistance with increase in BMI, especially central or abdominal obesity (increase in waist-to-hip circumference ratio). A reversal of overweight/obesity decreases the risk and in some people who already have Diabetes can decrease the degree of insulin resistance.
Family history – having a first degree relative with type 2 diabetes increases the risk of developing diabetes (2 to 3-fold) and the risk is even higher in those with both maternal and paternal history of type 2 diabetes (5-6 fold).
Race or Ethnicity – Long term prospective studies have shown an increased risk of developing diabetes in women of Asian, African America and Hispanic ethnicities when compared with whites.
Physical inactivity – A sedentary lifestyle leads to increase insulin resistance, decreased energy expenditure and weight gain and this is known to increase the risk of developing diabetes. Even without weight gain, physical inactivity increases the risk of type 2 diabetes.
Environmental Exposures – Chronic exposure to inorganic arsenic in drinking water, bisphenol A (a monomer used to make hard polycarbonate plastics), chronic exposure to organophosphate and chlorinated pesticides have been shown to increase the risk of developing diabetes.
Diet – besides increased caloric intake and weight gain certain types of foods and deficiency of some microelements are known to increase the risk of developing Diabetes:
Sugar sweetened beverages – soft drinks (Sodas) especially in children increase the risk of both weight gain and insulin resistance.
Western Diet – high in red meat, processed meat, high in fat, dairy products, sweets and desserts are associated with increased risk of obesity and developing diabetes as compared to a Prudent and Mediterranean diet.
Chromium deficiency – this is generally limited to hospitalized patients and those in the setting of malnutrition as most studies have conflicting results in normal individuals.
Diagnosis of Type 2 Diabetes Mellitus
Using the American Diabetes Association (ADA) diagnostic criteria, one of the following has to be met and, in the absence of unequivocal hyperglycemia, repeated to confirm the results:
Fasting plasma glucose of 126mg/dL (7.0mMol/L) or higher, or
A 2-hr plasma glucose of 200mg/dL (11.1mMol/L) or higher after a 75-mg oral glucose tolerance test (OGTT), or
A random plasma glucose of 200mg/dL (11.1mMol/L) or higher with classic symptoms of hyperglycemia or hyperglycemic crisis, or
Hemoglobin A1c of 6.5% or higher performed in a laboratory using a method that is NGSP certified and standardized to the DCCT assay.
Criteria for Pre-diabetes (at risk of Diabetes) include:
A1c of 5.7-6.4%
Fasting plasma glucose of 100 to 125mg/dL (5.6 to 6.9mMol/L) – impaired Fasting plasma glucose (IFG)
A 2-hr plasma glucose of 140-199mg/dL (7.8 to 11.0mMol/L) – impaired glucose tolerance (IGT)
Screening for Diabetes Mellitus
Testing for Diabetes or Pre-Diabetes in asymptomatic Adults should be considered in any of the following:
Adults age 45 years and older
Adults who are overweight (BMI ≥ 25 or ≥ in Asian Americans) with any of the following additional factors:
Physical inactivity
First degree relative with Diabetes mellitus
Hypertension (BP ≥140/90 or on treatment for Hypertension)
Pre-diabetes on previous testing
Women with polycystic ovary syndrome (PCOS)
History of cardiovascular disease
Women who delivered a baby >9lbs (4kg) or were diagnosed with Gestational Diabetes Mellitus
HDL cholesterol <35mg/dL (0.9mMol/L)
High risk race/ethnicity (African American, Latino, Asian American, Native American and Pacific Islanders)
If results are normal testing should be repeat at least at a minimum of 3-year intervals unless clinically indicated.
Treatment of type 2 Diabetes Mellitus
Unlike type 1, treatment of type 2 Diabetes is slightly complex and multifaceted, it can be broken down into lifestyle changes and medical (drug) treatment:
Lifestyle modification – This is by far the most important part of treatment of type 2 Diabetes. Since the main defect in type 2 diabetes is insulin resistance, the main focus should be decreasing factors that cause and/or increase insulin resistance (diet, obesity/overweight and sedentary lifestyle). As little as 10% weight loss can have a major impact on insulin resistance and control of diabetes. Amount and choice of food is important for both weight loss and your body’s response to insulin. Discussion diet and Diabetes to follow.
Medications – for those who cannot control their diabetes with lifestyle changes alone medications are added to achieve normal blood sugar. Choice of medications depends on your doctor’s assessment. Some of the medications being used include; Metformin, Sulfonylureas (glipizide, Glimeperide, Glibenclamide etc.), Januvia, Invokana, and insulin amongst others. A more detailed discussion on different type of Type 2 Diabetes meds will be posted.
Bariatric surgery – since weight loss is central to management of type 2 diabetes people with a body mass index (BMI) above 35 with no contraindications can benefit from bariatric surgery. There are studies showing major improvement and even complete disease remission after bariatric surgery.
Complications
Diabetes affects both small (microvascular) and large (macrovascular) blood vessels of major organs, usually after a long period of uncontrolled diabetes. Some complications can be life threatening while others tend to cause long term disability resulting in loss of work, production and decreased quality of life. Some of the major long-term complications include:
Retinopathy (Eye damage) – Growth of brittle blood vessels in the retina (at the back of the eye) and swelling of the macular leads to vision loss and eventually blindness. Diabetic retinopathy is the leading cause of blindness in non-elderly adults in developed countries. Annual screening by an ophthalmologist is recommended to identify and treat diabetes related eye conditions early while they are still reversible.
Nephropathy (kidney damage) – initially seen as leakage of protein on a urine test, this can lead to chronic renal failure requiring dialysis. Diabetes is the most common cause of adult renal failure in developed countries. A screening urine test to detect leakage of protein can identify those with early kidney manifestations of diabetes and allow for aggressive treatment of diabetes and close monitoring of kidney function.
Nerve damage (neuropathy) – different nerves are affected at different times and rates with sensory nerves being the first to be affected. Usually in a glove and stocking distribution, starting in the feet and then spread to other nerves. When the autonomic nervous system is also affected this can result in loss of bladder control, abnormal heart rate, low blood pressure with lightheadedness, delayed emptying of the stomach and abnormal sweating patterns.
Amputations – Diabetes is the major cause of non-traumatic amputations in the US, the incidence is even higher in those with peripheral neuropathy due to inability to sense and detect infection and skin breakdown on affected feet. The immune system is also not as robust in people with diabetes and this leads to a decrease in the ability to fight infections, in fact infection from bacterial organisms tends to spread faster in people with high blood sugar and this can lead to life threatening foot infections that can only be cured by amputation
Heart disease and Peripheral vascular disease – when bigger blood vessels are affected (macrovascular) the effects can be catastrophic. Development of plaque and eventually occlusion of heart blood vessels can lead to a heart attack and sometimes sudden death, especially if someone is far from the hospital. Other major complications include stroke, peripheral arterial disease (with pain on lower extremities) and aneurysm of the aorta (major blood vessel from the heart).
Other complications include:
Erectile dysfunction
Muscle wasting
Recurrent infections (especially fungal)
Delayed wound healing and response to infections
Depression
Periodontal disease (gum disease)
Acute complications are usually life threatening and require urgent/emergent hospital management, these include:
Diabetic Ketoacidosis (DKA) – when insulin level is low the liver turns to fatty acids to produce ketone bodies (alternate source of energy) and build up of these ketone bodies results in acidity in the body. This happens within minutes to hours with features such as dehydration, high blood sugar, nausea, vomiting, stomach pain, and sometimes altered mental status. DKA is more common in type 1 diabetes but can still happen in some people with type 2 diabetes (Ketosis prone Diabetes)
Diabetic coma (Non-ketotic hyperosmolar Coma) – is the equivalent of DKA in type 2 diabetes, since insulin is usually normal (remember the problem is insulin resistance) there is no acid build up. However blood sugar is so high such that dehydration ensues and certain cells, especially neurons, cannot function in this condition hence leading to coma and risk of death if untreated.
Hypoglycemia (low blood sugar) – a complication of overtreatment with certain diabetic medications. More common in those taking insulin and sulfonylureas (like Glipizide, Glimepiride, Glyburide). Some factors that may increase the risk of hypoglycemia include: old age, missed meals, kidney disease, liver disease, heart failure, medication error (mixing up insulin types), and medications that can lower blood sugar or change metabolism of diabetes medications. People who have recurrent low blood sugar can lose awareness of low blood sugar, a condition know as Hypoglycemia-associated autonomic failure. Hypoglycemia unawareness can be deadly especially during sleeping hours.
