At-Home Device for Glucose and Cholesterol Screening

US Pharm. 2007;32(9):74-76.

Diabetes is the fifth leading cause of death worldwide.¹ It is characterized by increased levels of blood sugar resulting from defects in insulin secretion, insulin sensitivity, or both. There are two types of diabetes; type 1 diabetes results from an autoimmune disorder that causes beta-cell destruction, while type 2 diabetes results from both a progressive defect in insulin secretion and insulin sensitivity to receptors.² Research has demonstrated that improved glycemic control is associated with sustained, decreased rates of microvascular (i.e., retinopathy and nephropathy), macrovascular (i.e., myocardial infarction and stroke), and neuropathic complications.

Cardiovascular disease, a major cause of death in the United States, kills nearly 500,000 Americans each year.³ The principle causative factor, hyperlipidemia, is due to an elevation of one or more of the following: cholesterol, phospholipids, or triglycerides circulating in the plasma. Uncontrolled levels of lipids can increase the risk of premature death.⁴

Monitoring
Physical activity, weight loss, and proper diet can help maintain normal levels of glucose and cholesterol. One very important method of tracking the progress of diabetes is to monitor the patient's glucose on a regular basis.⁵ Fortunately, there are many devices that allow such readings in the convenience of one's home. However, testing for cholesterol levels is almost exclusively performed in the physician's office by drawing blood and sending the sample to a lab at another facility, making cholesterol testing difficult to obtain for some patients. Fortunately, the Q.STEPS Biometer G/C Dual Monitoring System (Q.STEPS) is a home diagnostic device that checks both glucose and cholesterol levels, affording patients' convenience and accuracy.

Major clinical trials assessing the impact of glycemic control on diabetes complications have included self-monitoring of blood glucose (SMBG) as part of multifactorial interventions, suggesting that SMBG is a component of effective therapy. SMBG allows patients to evaluate their individual response to therapy and assess whether glycemic targets are being achieved. The most common values measured for diabetes are glucose levels and glycosated hemoglobin. The American Diabetes Association's 2006 practice guidelines recommend the following clinical targets for adults with diabetes: hemoglobin A1c below 7%, fasting blood glucose at 90 to 130 mg/dL, and a postprandial plasma glucose level of less than 180 mg/dL.²

Monitoring cholesterol is an integral part of cholesterol management and commonly includes a fasting lipoprotein profile. This profile measures total cholesterol, low-density lipoprotein (LDL) cholesterol, triglyceride, and high-density lipoprotein (HDL) levels in the plasma. The Adult Treatment Panel (ATP) III guidelines recommend the following clinical targets for adults: total cholesterol level of less than 200 mg/dL, LDL cholesterol level of less than 100 mg/dL, triglyceride level of less than 150 mg/dL, and HDL cholesterol level of greater than 60 mg/dL.⁶

Q.STEPS Biometer G/C Dual Monitoring System
Q.STEPS is intended for in vitro diagnostic use with whole human blood. The system consists of a user's manual, a calibration chip, glucose test strips, cholesterol test strips, a control solution, lancets, alcohol swabs, two AAA batteries, a quick reference card, and a carrying case.

Before using the device to check for blood glucose and/or cholesterol levels, a system check must be performed with the control solution. This should be performed at least once every three months, if the patient experiences symptoms that do not match the results of the device, or when a new vial of test strips is opened.

Q.STEPS can accurately give glucose and cholesterol readings between the ranges of 50 to 400 mg/dL and 150 to 350 mg/dL, respectfully, in less than 30 seconds. Excessive glucose and cholesterol readings of 400 and 350 mg/dL, respectfully, are displayed as "Hi," while those below 50 and 150 mg/dL, respectfully, are displayed as "Lo"; neither result will display a numerical value. The device contains a built-in memory bank that is capable of storing the last 99 glucose readings and the last 50 cholesterol readings. Patient instructions are detailed in Table 1 .

Limitations
Separate test strips must be used to monitor glucose and cholesterol, and the two readings cannot be performed simultaneously. Additionally, the meter does not indicate whether the blood sample is adequate; an inaccurate glucose or cholesterol reading may be obtained if the sample is not sufficient. In order to obtain accurate results, approximately 3 and 15 mcL of blood should be obtained for glucose and cholesterol testing, respectively.

Efficacy
Glucose: Precision results for Q.STEPS were determined following the National Committee for Clinical Laboratory Standards (NCCLS) guidelines. The company used glucose-spiked blood in concentrations of 50, 80, 120, 200, and 400 mg/dL. These samples were first measured by the Yellow Springs Instrument (YSI), a standard biochemical analyzer, as a reference, and were subsequently measured using Q.STEPS. Readings were taken twice per day for 20 days, and each concentration level was applied to three lots of test strips. Precision results were all within 6% and are presented in Table 2.

Method comparison studies for linearity were performed at three different clinical sites. This correlation study utilized finger-stick, whole-blood samples for comparison of the Q.STEPS and YSI. It was shown that the glucose test results from Q.STEPS had a linear relation of Y = 0.9976x + 1.8331 with a linear regression coefficient of R = 0.95, constituting compliance with universal guidelines.

Cholesterol: Precision results for the Q.STEPS were determined following NCCLS guidelines. The company used cholesterol-spiked blood in concentrations of 190, 200, 240, and 260 mg/dL. These samples were first measured by Cobas, as a reference, and were then measured by Q.STEPS. Readings were taken twice per day, and each concentration was applied to three lots of test strips. Precision results were all within 6% and are presented in Table 3.

Method comparison studies for linearity were compared with the Abel-Kendall reference method performed in a CDC-certified Cholesterol Reference Method Laboratory Network (CRMLN). External studies were also done at three clinical sites by lay-users. A total of 456 patients participated in the clinical trial. It was shown that the glucose results from Q.STEPS had a linear relation of Y = 0.9411x + 16.555, with a linear regression coefficient of R = 0.986. The accepted standards for cholesterol testing, CRMLN states that the regression analysis coefficient variation should be r = 0.989. The regression analysis meets cholesterol-monitoring requirements, constituting compliance with universal guidelines. 

Conclusion
Blood glucose monitoring is a cornerstone in controlling diabetes, and blood cholesterol monitoring has an important role in preventing cardiovascular disease in patients. Q.STEPS provides patients with the convenience of having one machine to monitor two different conditions in the comfort of their homes. Additional information about Q.STEPS is available online at www.biomedixusa.com or via telephone at (888) 246-6318.

References
1. Dream Trial Investigators, Bosch J, Yusuf S, Gerstein HC, et al. Effect of ramipril on the incidence of diabetes. N Engl J Med. 2006;355:1551-1562.
2. American Diabetes Association. Standards of medical care in diabetes--2007. Diabetes Care . 2007;30:S4-S41..
3. Centers for Disease Control and Prevention Web site. Available at: www.cdc.gov/diabetes/pubs/pdf/ndfs_2005.pdf. Accessed February 5, 2007.
4. Nissen S, Tuzcu EM, Schoenhagen P, et al. Statin therapy, LDL cholesterol, C-reactive protein, and coronary artery disease. N Engl J Med. 2005;352:29-38.
5. McMahon GT, Arky RA. Inhaled insulin for diabetes mellitus. N Engl J Med. 2007;356:497-502.
6. Grundy SM, Cleeman JI, Merz NB, et al. Implications of recent clinical trials for the national cholesterol education program adult treatment panel III guidelines. Circulation. 2004;110:227-239.
7. Biomedix Inc. Q.STEPS Biometer G/C User's Manual. Fremont, CA, 2004.
8. U.S. Food and Drug Administration. Available at: www.fda.gov. Accessed February 14, 2007.

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