For the first time, the 2019 American Diabetes Association’s ‘Standards of Medical Care in Diabetes’ includes a dedicated section on diabetes technology.
In it first year, the Diabetes Technology section of the ADA’s “Standards of Medical Care in Diabetes” focuses on insulin delivery and glucose monitoring. In future years, the ADA intends to include software as a medical device, privacy, cost, technology-enabled diabetes education and support, telemedicine, and other issues. The 2019 “Standards” were published early this year and updated this summer.
Diabetes technology topics include:
- Insulin syringes and pens.
- Insulin pumps.
- Self-monitoring of blood glucose.
- Glucose meter accuracy.
- Continuous glucose monitoring.
- Real-time continuous glucose monitoring.
- Intermittently scanned continuous glucose monitoring.
- Automated insulin delivery.
Insulin syringes and pens
For people with diabetes who require insulin, insulin syringes or insulin pens may be used for insulin delivery with consideration of patient preference, insulin type and dosing regimen, cost, and self-management capabilities, says the ADA. Insulin pens or insulin injection aids may be considered for patients with dexterity issues or vision impairment.
Another insulin delivery option is a disposable patch-like device, which provides a continuous, subcutaneous infusion of rapid-acting insulin (basal), as well as 2-unit increments of bolus insulin at the press of a button, says the ADA.
Insulin pumps
Most adults, children, and adolescents with type 1 diabetes should be treated with intensive insulin therapy with either multiple daily injections or an insulin pump, according to the ADA. Insulin pump therapy may be an option for all children and adolescents, especially in children under 7 years of age.
Continuous subcutaneous insulin injection, or insulin pumps, have been available in the U.S. for 40 years. These devices deliver rapid-acting insulin throughout the day to help manage blood glucose levels. Most insulin pumps use tubing to deliver insulin through a cannula, while a few attach directly to the skin, without tubing.
Common barriers to pump therapy adoption in children and adolescents are concerns regarding the physical interference of the device, discomfort with idea of having a device on the body, therapeutic effectiveness, and financial burden, says the ADA.
Self-monitoring of blood glucose
Most patients using intensive insulin regimens (multiple daily injections or insulin pump therapy) should assess glucose levels using self-monitoring of blood glucose (or continuous glucose monitoring).
For patients with type 1 diabetes using continuous glucose monitoring (CGM), the greatest predictor of A1C lowering for all age groups is frequency of sensor use, which studies show is highest in those aged 25 years and over, and lower in younger age groups. Similarly, for self-monitoring of blood glucose (SMBG) in patients with type 1 diabetes, a correlation exists between greater SMBG frequency and lower A1C.
In people with type 2 diabetes not using insulin, routine glucose monitoring may be of limited additional clinical benefit, according to the ADA. However, “[f]or some individuals, glucose monitoring can provide insight into the impact of diet, physical activity, and medication management on glucose levels. Glucose monitoring may also be useful in assessing hypoglycemia, glucose levels during intercurrent illness, or discrepancies between measured A1C and glucose levels when there is concern an A1C result may not be reliable in specific individuals.”
Glucose meter accuracy
Patients assume that if their glucose monitor is FDA-cleared, it must be accurate. But that is not always the case, says the ADA. Factors limiting accuracy include:
- Counterfeit strips. Patients should be advised against purchasing or reselling preowned or second-hand test strips. Only unopened vials of glucose test strips should be used to ensure SMBG accuracy.
- Currently available glucose monitors use an enzymatic reaction linked to an electrochemical reaction – either glucose oxidase or glucose dehydrogenase, says the ADA. Glucose oxidase monitors are sensitive to the oxygen available and should only be used with capillary blood in patients with normal oxygen saturation. Glucose dehydrogenase monitors are not sensitive to oxygen.
- Because the reaction is sensitive to temperature, all monitors have an acceptable temperature range. Most will show an error if the temperature is unacceptable, but a few provide a reading and a message indicating that the value may be incorrect, according to the ADA.
- Interfering substances. A few physiologic and pharmacologic factors interfere with glucose readings. Most interfere only with glucose oxidase systems.
Continuous glucose monitoring
There are two types of continuous glucose monitoring:
- Real-time CGM, which continuously reports glucose levels and includes alarms for hypoglycemic and hyperglycemic excursions.
- Intermittently scanning CGM (isCGM), which is approved for adult use only. Intermittently scanning CGM does not have alarms and does not communicate continuously – only on demand. It is reported to have a lower cost than systems with automatic alerts.
Two CGM devices are now approved by the FDA for making treatment decisions without SMBG confirmation (i.e., without calibration using a blood sample from the fingertip, sometimes called adjunctive use): Dexcom’s G5 Mobile Continuous Glucose Monitoring System, and the FreeStyle Libre Flash Glucose Monitoring System.
Real-time continuous glucose monitors
Real-time continuous glucose monitoring should be considered in children and adolescents with type 1 diabetes, whether using multiple daily injections or continuous subcutaneous insulin infusion, as an additional tool to help improve glucose control and reduce the risk of hypoglycemia, says the ADA.
For adults: real-time continuous glucose monitoring:
- Can be a useful tool to lower A1C in adults with type 1 diabetes who are not meeting glycemic targets, in conjunction with intensive insulin regimens.
- May be a useful tool in those with hypoglycemia unawareness and/or frequent hypoglycemic episodes.
- Should be used as close to daily as possible for maximum benefit.
- May be used effectively to improve A1C levels and neonatal outcomes in pregnant women with type 1 diabetes.
Sensor-augmented pump therapy with automatic low-glucose suspend may be considered for adults with type 1 diabetes at high risk of hypoglycemia to prevent episodes of hypoglycemia and reduce their severity.
Intermittently scanned continuous glucose monitoring
Intermittently scanned continuous glucose monitor use (isCGM) may be considered as a substitute for self-monitoring of blood glucose in adults with diabetes requiring frequent glucose testing, says ADA. isCGM (sometimes referred to as “flash” CGM) measures glucose in interstitial fluid through a <0.4 mm–thick filament inserted under the skin. It has been available in Europe since 2014 and was approved by the FDA for use in adults in the U.S. in 2017.
The personal version of isCGM has a receiver that, after scanning over the sensor by the individual, displays real-time glucose values and glucose trend arrows. The data can be uploaded and a report created using available software. In the professional version, the patient does not carry a receiver; the data are blinded to the patient and the device is downloaded in the diabetes care provider’s office using the provider’s receiver and the software.
Studies in adults with diabetes indicate isCGM has acceptable accuracy when compared with SMBG, although the accuracy may be lower at high and/or low glucose levels. Studies comparing the accuracy of isCGM with real-time CGM show conflicting results. isCGM may decrease the risk of hypoglycemia in individuals with type 1 or type 2 diabetes. A growing number of studies suggest similar good performance and potential for benefit in special populations, including pregnant women with diabetes, individuals with type 1 diabetes and hypoglycemia unawareness, and children, although accuracy could be decreased in younger children.
Automated insulin delivery
Automated insulin delivery systems may be considered in children (>7 years) and adults with type 1 diabetes to improve glycemic control, according to ADA. These systems consist of three components: an insulin pump, a continuous glucose sensor, and an algorithm that determines insulin delivery. With these systems, insulin delivery cannot only be suspended but also increased or decreased based on sensor glucose values. Emerging evidence suggests such systems may lower the risk of exercise-related hypoglycemia and may have psychosocial benefits.
While eventually insulin delivery in closed-loop systems may be truly automated, meals must currently be announced. A so-called hybrid approach, hybrid closed-loop (HCL), has been adopted in first-generation closed-loop systems and requires users to bolus for meals and snacks. The FDA has approved the first HCL system for use in those as young as 7 years of age.
Source: “Standards of Medicare Care in Diabetes,” American Diabetes Association, https://care.diabetesjournals.org/content/27/suppl_1/s15