A 34-year-old laborer comes to the office because of a 2 kg (5 lb) weight loss and an increased appetite. He has diabetes mellitus and has been taking insulin in divided doses. He says that home monitoring of his serum glucose concentration has shown values from 15 mmol/L to 17.8 mmol/L.
Which of the following is the most appropriate management?
Correct Answer D:
This patient has inadequately treated insulin-dependent diabetes. The goal serum glucose for therapy is < 6.6 mmol/L. Since there is no indication that the insulin type is incorrect (hypoglycemia), the patient simply requires an increased dosage of his current insulin type.
Metformin is an oral antihyperglycemic agent that acts by increasing peripheral utilization of glucose. The primary purpose of medications such as this is to delay or avoid the requirement for exogenous insulin. Once a patient is on insulin, these drugs are of little benefit. Secondarily, most patients with non-insulin dependent diabetes have relative “insulin resistance” and it is for this reason that glucose utilization drugs are employed as first line management. This patient’s symptoms of increased weight loss and appetite are a function of his poor glucose control, not of inadequate caloric intake. Poorly controlled insulin dependent diabetics are often thin as they waste muscle to liberate glucose in an attempt to provide glucose for the body. The defect is with the inability to utilize the glucose already present so the end result is hyperglycemia and muscle wasting. For similar reasons, there is no need to alter his caloric distribution.
A 75-year-old white male with well-controlled type 2 diabetes mellitus is scheduled for an abdominal CT scan with oral and intravenous iodinated contrast.
Which one of the following medications should be withheld 48 hours before and after the procedure?
Metformin should be withheld before and after radiographic procedures with contrast, due to its interaction with iodinated contrast materials. This interaction may cause impaired renal function or lactic acidosis. The other drugs listed do not carry this risk.
Metformin (Glucophage), which is normally used in the management of diabetes mellitus, has also been shown to have a beneficial effect in:
Correct Answer C: Recent data suggests that insulin resistance and hyperinsulinemia are important in the pathogenesis of polycystic ovary syndrome (PCOS). Treatment with drugs that reduce glucose levels, such as metformin, has been shown to correct many of the metabolic abnormalities associated with PCOS. Such correction results in resumption of ovulation, decreased insulin resistance, and improved beta-cell function; it also produces improvement in cardiovascular risk factors such as dyslipidemia and impaired fibrinolysis.
Thiazolidinedione antidiabetic agents include rosiglitazone (Avandia) and pioglitazone (Actos).
Their mechanism of action is:
Correct Answer A: Thiazolidinediones decrease insulin resistance by binding to nuclear peroxisome proliferators-activated receptors. They decrease gluconeogenesis and have no effect on insulin release or production by the pancreas, or on intestinal carbohydrate absorption.
A 45-year-old male was recently diagnosed with type 2 diabetes mellitus. He presents to your office today to begin oral antihyperglycemic therapy. Results of a fasting serum metabolic panel include the following:
Laboratory Findings:
Which one of the following medications would be contraindicated in this patient?
Correct Answer C:
Maintaining good blood glucose control is important for preventing the microvascular complications of diabetes mellitus. A number of oral antihyperglycemic agents are available, but each drug class has unique adverse effects that affect their appropriateness for individual patients. In this case, the patient has evidence of renal impairment (serum creatinine ≥1.5 mg/dL for men and ≥1.4 mg/dL for women). This leads to an increased risk of lactic acidosis when a biguanide such as metformin is used. Other contraindications to biguanide use include hepatic dysfunction, congestive heart failure, metabolic acidosis, dehydration, and alcoholism. The sulfonylureas include chlorpropamide (1st generation) and glipizide (2nd generation). They are associated with weight gain and hypoglycemia. α-Glucosidase inhibitors (e.g., acarbose) are less effective than other drug classes as monotherapy and can be associated with gastrointestinal side effects. Thiazolidinediones (e.g., pioglitazone) are associated with weight gain, edema, and potential liver injury.
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