Blood glucose monitoring: update on terms and recommendations

Since the last Canadian diabetes guidelines were published in 2018,1 new blood glucose monitoring technologies have emerged. These advances have prompted the need for an update on blood glucose monitoring terminology and monitoring recommendations. To help pharmacists understand the latest terminology and recommendations, this column summarizes key points in Diabetes Canada’s 2021 update on blood glucose monitoring in adults and children with diabetes.2 Updated terminology Due to the expanding technology, terminology has been updated to differentiate the various methods for monitoring blood glucose (Table 1). Pharmacists should expect to see these new terms increasingly used in published literature. Read: QUIZ: Test your knowledge of diabetes and COVID-19 infection A1C is a commonly used marker of blood glucose control; however, it is a measure of chronic glycemic levels over months and does not provide information that can be used to guide immediate or short-term decisions. Pharmacists can expect to see a variety of new glucose metrics provided by the newer blood glucose monitoring modalities, including time in range (TIR), time above range (TAR), time below range (TBR) and glycemic variability.3 Updated blood glucose monitoring recommendations The following points summarize Diabetes Canada’s 2021 key recommendations for blood glucose monitoring in adults, children and adolescents, with recent changes identified in bold. In most individuals*, A1C should be measured about every three months, or more frequently if there are changes in therapy or during pregnancy. When glycemic targets have been consistently achieved, testing at least every six months is recommended. In individuals* using insulin more than once daily, capillary blood glucose (CBG) testing should be used as an essential part of diabetes management for type 1 diabetes, for type 2 diabetes, and for children and adolescents. It should be undertaken at least three times per day and include both pre- and post-prandial measurements. For individuals with type 2 diabetes (including children and adolescents) on once-daily insulin in addition to noninsulin antihyperglycemic agents, testing at least once a day at variable times is recommended. In individuals* with type 2 diabetes not receiving insulin therapy, the frequency of CBG testing should be individualized depending on type of antihyperglycemic agents, A1C level and risk of hypoglycemia. a) When A1C targets are not being reached, structured CBG testing should be instituted (including a 7-point profile [fasting, preprandial/2-hour postprandial at each meal, bedtime]; every 1–3 months) to improve A1C for adults, children and adolescents. b) If achieving A1C targets or receiving antihyperglycemic medications not associated with hypoglycemia, daily CBG testing is not recommended except during illness or when at risk of hyperglycemia (e.g., surgery, steroid treatment), when more frequent testing may be required. In all individuals* with diabetes, more frequent CBG testing (4 times per day and/or overnight) is recommended when A1C is not at target or there are episodes of hypoglycemia, to identify the safest and most effective clinical approach to improve blood glucose levels. In individuals with type 1 diabetes using basal-bolus insulin therapy or continuous subcutaneous insulin infusion (CSII): a) Real-time continuous glucose monitoring (rtCGM) should be used to: i. reduce A1C and increase TIR; ii. reduce duration and incidence of hypoglycemia; iii. improve aspects of diabetes- specific quality of life (in adults); iv. increase treatment satisfaction (in adults using CSII). b) Intermittently scanned continuous glucose monitoring (isCGM) may be used to: i. increase TIR; ii. reduce frequency and duration of hypoglycemia; iii. increase treatment satisfaction. In adults with type 1 diabetes with impaired awareness of hypoglycemia or recent severe hypoglycemia: a) rtCGM should be used to reduce incidence of hypoglycemia and severe hypoglycemic events compared with CBG testing b) rtCGM is recommended to reduce time in hypoglycemia compared with isCGM. In adults with type 2 diabetes using basal-bolus insulin therapy who have not achieved their A1C target, who are willing and able to use these devices on a nearly daily basis: a) rtCGM may be used to reduce A1C and duration of hypoglycemia b) isCGM may be used as an alternative to CBG testing to reduce frequency and duration of hypoglycemia. In pregnant women with type 1 diabetes, rtCGM should be used to increase TIR and reduce TAR, and reduce the risk of large for gestational age infants, neonatal hypoglycemia and neonatal intensive care unit admissions > 24 hours. Women with gestational diabetes or type 2 diabetes during pregnancy: a) should perform CBG testing four times daily (fasting and postprandially) for one week to assess blood glucose levels and need for pharmacotherapy: i. in women who do not require antihyperglycemic medications, CBG testing can be reduced to four times per day on alternate days ii. in women who require insulin therapy, CBG testing should be performed four times daily, both fasting and postprandially, to improve pregnancy outcomes. *Individuals include adults, children and adolescents Summary The biggest takeaway is that you can help encourage all of your patients living with diabetes to identify the safest and most effective clinical approach to improve blood glucose levels when A1C is not at target or there are episodes of hypoglycemia. The question is—which approach is the recommended one? Your “cheat sheet” is right above! Shelley Diamond, BScPhm, is a pharmacist and co-founder of www.diabetescarecommunity.ca, an extensive online resource for Canadians living with diabetes, their families and healthcare professionals. REFERENCES 1. Diabetes Canada Clinical Practice Guidelines Expert Committee. Diabetes Canada 2018 clinical practice guidelines for the prevention and management of diabetes in Canada. Can J Diabetes 2018;42(Suppl 1):S1-325. 2. Diabetes Canada Clinical Practice Guidelines Expert Working Group. Blood glucose monitoring in adults and children with diabetes: update 2021. Can J Diabetes 2021;45:580-7. https:// www.canadianjournalofdiabetes.com/action/ showPdf?pii=S1499-2671%2821%2900195-7 (accessed December 7, 2021). 3. Danne T, Nimri R, Battelino T, et al. International consensus on use of continuous glucose monitoring. Diabetes Care 2017;40:1631-40. Read: Diabetes progression significantly higher in diabetes patients who use statins

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Blood glucose monitoring: update on terms and recommendations

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Shelley Diamond

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