Everything you did and did NOT want to know about glucometers and CGMS October 20 th, 2013

Agenda Development of Self Glucose Monitoring Glucometers – How do they work? Glucometers – How well do they work? Some Best Practices CGSM Future? References Q & A

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Self Glucose Monitoring Transition from urine to blood testing in the 1960s First commercial meter was $650 and was intended for clinical use in 1970 (Ames Reflective Meter) Self glucose monitoring only became part of standards of care in the US in the early 1980s Biggest diabetes development since insulin in 1920s Allowed people to achieve better glucose control Since then, meters have become smaller, cheaper and more accessible to diabetics Continuous Glucose Monitoring Systems (CGM) is the latest “event” of glucose monitoring within the last decade

How do they Work Basic Components: Disposable “Strip” that contains an enzyme that reacts with glucose in blood, a “meter” that interprets the reaction A chemical reaction occurs when the enzyme is exposed to blood that creates an electrical current based on the amount of glucose in the blood and the meter translates the current to a glucose reading Shift in chemicals used in strips last decade but now most meters use Glucose Oxidase method The US standard is mg/dl which is milligrams of sugar per deciliter of blood Plasma (lab measured) vs. Whole Blood (home measured) – produce different results HOWEVER home meters produce “plasma equivalent” results

Accuracy Not all meters are created equal! FDA accuracy standards is that 95% of readings are +/- 20% for reference readings of >= 75mg/dl and within 15 points < 75 mg/dl For example 300 could actually be 360 or 240 and 60 could actually be 45 or 75 mg/dl Recent awareness inaccuracy of manufacturers products and relaxed standards have caused the T1D community to put pressure on law makers and manufacturers to improve their products Many manufacturers test accuracy at >200 and <60 and not in normal range.

Accuracy (cont) Recent studies on meter accuracy shows wide range in accuracy (how close to “lab” result) and precision (repeatability) Strips results are variable and can vary lot to lot, some meters used coding to help this but now most meters have moved away from this practice Studies show human error contributes significantly to meter inaccuracy (see best practices) CGM systems are built on top of meter readings so accuracy is further degraded

Best Practices Wash and completely dry hands with warm water before taking sample Make sure fingers are “warm” to ensure blood flow (gentle massage before obtaining sample can help) Make sure enough blood is provided to strip Tune lancelet device with proper “tip” and dial in “depth” to get enough puncture to obtain enough blood but never too deep where painful Non finger alternative sites (forearms, etc.) have been found to be much less accurate and “delayed” results than fingers Rotate finger locations to avoid callusing and you can even use top of the fingers

Best Practices (cont) Alcohol can cause callusing of fingers and is discouraged, Waterless sanitizers especially with lotions can affect results, better to “lick” finger clean if in a jam! Double check if reading does not make sense (do 2 out of 3 if you get different results) Using > 250mg of Vitamin C daily has been found to cause meter readings to be lower than expected Protect your strips from excess heat and cold KEEP A LOG and/or review meter readings regularly Use best practices with an accurate meter!!! Glucose level is the most important piece of data in your diabetic care. High blood sugar causes complications and that’s a fact!

Best Practices (cont) Change lancelet once a week minimally and never use dull lancelet Never share meter, if so be sure to change lancelet before and after and sanitize lancelet device tip Hydrogen peroxide does a good job getting blood stains out of clothes

When to Check? Upon rising in the morning Immediately before breakfast Before each meal or snack Two hours after meals and snacks At bedtime Before and after exercising, shopping, or running Whenever you are hungry or suspect that your blood glucose may be higher or lower than usual Before driving a car or operating heavy machinery and hourly while engaging in these activities You can never check too often!!!

CGM Systems Gaining popularity as a number of products are on the market and are now covered by most insurance Separate sensor that transmits glucose information (current measurement) to a separate receiver Sensor resides in subcutaneous fat and uses interstitial fluid (not blood) and is inserted with a needle and then needle removed similar to pump infusion sets Sensors can be worn 3-7 days depending on product Requires calibration by glucose meter readings every 6-12 hours Most CGM systems takes readings every 5 minutes Can download sensor data to computer and get various reports which are very useful for analyzing basil (fasting) patterns and bolus calculation analysis Some sensors are integrated with Pump

CGM Systems (cont) Accuracy is +/ % and since it is calibrated based on meter readings, error is compounded Sensor readings lag up to 20 minutes behind finger stick readings due to using interstitial fluid not blood Should only be used for trending and alarming on potential rising/falling rates and low/high thresholds which prompt you to take glucose reading and treat accordingly Sensors are getting more accurate and will get integrated with other devices like your cell phone not just pumps Glucose monitoring is one of two major hurdles to an artificial pancreases since readings lag and even our fastest acting insulin is no good enough to achieve normalized sugars

The Future? More accurate and precise meters and strips More accurate and precise CGMS Glucose data sent to cell phones (FDA roadblock) Already good smartphone apps Devices implanted in body exposed to blood to give extremely accurate glucose readings FDA generally is a road block on new technology so don’t expect any major breakthroughs to the market anytime soon

References Glucose Meters: A Review of Technical Challenges to Obtaining Accurate Results (Ksenia Tonyushkina, M.D. 1 and James H. Nichols, Ph.D., DABCC, FACB)Ksenia TonyushkinaJames H. Nichols System Accuracy Evaluation of 43 Blood Glucose Monitoring Systems for Self-Monitoring of Blood Glucose according to DIN EN ISO (Guido Freckmann, M.D., Christina Schmid, Ph.D., Annette Baumstark, Ph.D., Stefan Pleus, M.S., Manuela Link, M.E., and Cornelia Haug, M.D.) Dr. Bernstein's Diabetes Solution: The Complete Guide to Achieving Normal Blood Sugars (p. 515).

Q & A