Type 2 diabetes mellitus consists of an array of dysfunctions characterized by hyperglycemia and resulting from the combination of resistance to insulin action, inadequate insulin secretion, and excessive or inappropriate glucagon secretion. See the image below.
Simplified scheme for the pathophysiology of type 2 diabetes mellitus.
See Clinical Findings in Diabetes Mellitus, a Critical Images slideshow, to help identify various cutaneous, ophthalmologic, vascular, and neurologic manifestations of DM.
Signs and symptoms
Many patients with type 2 diabetes are asymptomatic. Clinical manifestations include the following:
Classic symptoms: Polyuria, polydipsia, polyphagia, and weight loss
Yeast infections (eg, balanitis in men)
See Presentation for more detail.
Diagnostic criteria by the American Diabetes Association (ADA) include the following
A fasting plasma glucose (FPG) level of 126 mg/dL (7.0 mmol/L) or higher, or
A 2-hour plasma glucose level of 200 mg/dL (11.1 mmol/L) or higher during a 75-g oral glucose tolerance test (OGTT), or
A random plasma glucose of 200 mg/dL (11.1 mmol/L) or higher in a patient with classic symptoms of hyperglycemia or hyperglycemic crisis
Whether a hemoglobin A1c (HbA1c) level of 6.5% or higher should be a primary diagnostic criterion or an optional criterion remains a point of controversy.
Indications for diabetes screening in asymptomatic adults includes the following
Sustained blood pressure >135/80 mm Hg
Overweight and 1 or more other risk factors for diabetes (eg, first-degree relative with diabetes, BP >140/90 mm Hg, and HDL < 35 mg/dL and/or triglyceride level >250 mg/dL)
ADA recommends screening at age 45 years in the absence of the above criteria
See Workup for more detail.
Goals of treatment are as follows:
Microvascular (ie, eye and kidney disease) risk reduction through control of glycemia and blood pressure
Macrovascular (ie, coronary, cerebrovascular, peripheral vascular) risk reduction through control of lipids and hypertension, smoking cessation
Metabolic and neurologic risk reduction through control of glycemia
Recommendations for the treatment of type 2 diabetes mellitus from the European Association for the Study of Diabetes (EASD) and the American Diabetes Association (ADA) place the patient’s condition, desires, abilities, and tolerances at the center of the decision-making process.
The EASD/ADA position statement contains 7 key points:
Individualized glycemic targets and glucose-lowering therapies
Diet, exercise, and education as the foundation of the treatment program
Use of metformin as the optimal first-line drug unless contraindicated
After metformin, the use of 1 or 2 additional oral or injectable agents, with a goal of minimizing adverse effects if possible
Ultimately, insulin therapy alone or with other agents if needed to maintain blood glucose control
Where possible, all treatment decisions should involve the patient, with a focus on patient preferences, needs, and values
A major focus on comprehensive cardiovascular risk reduction
The 2013 ADA guidelines for SMBG frequency focus on an individual’s specific situation rather than quantifying the number of tests that should be done. The recommendations include the following
Patients on intensive insulin regimens – Perform SMBG at least before meals and snacks, as well as occasionally after meals; at bedtime; before exercise and before critical tasks (eg, driving); when hypoglycemia is suspected; and after treating hypoglycemia until normoglycemia is achieved.
Patients using less frequent insulin injections or noninsulin therapies – Use SMBG results to adjust to food intake, activity, or medications to reach specific treatment goals; clinicians must not only educate these individuals on how to interpret their SMBG data, but they should also reevaluate the ongoing need for and frequency of SMBG at each routine visit.
Approaches to prevention of diabetic complications include the following:
HbA1c every 3-6 months
Yearly dilated eye examinations
Annual microalbumin checks
Foot examinations at each visit
Blood pressure < 130/80 mm Hg, lower in diabetic nephropathy
Statin therapy to reduce low-density lipoprotein cholesterol
See Treatment and Medication for more detail.