C G M

Continuous Gucose Monitoring (CGM) in resource limited settings

CGM sensor attached to abdomen and hand-held monitor. © Elizabeth Snouffer
Continuous Glucose Monitoring (CGM) is a relatively new technology which has the potential to assist people living with type 1 or type 2 diabetes and treated with insulin to achieve the goal of optimum control of blood glucose. Here, Kaushik Ramaiya considers the advantages and some of the disadvantages of this technology and comments on it from the point of view of a health professional working in a resource limited setting. In the final analysis, judgements as to its usefulness will be based not only on its effectiveness but also its cost effectiveness. However, as with many other similar developments, the only economic evidence we have to date relates to more affluent settings.

Continuous glucose monitoring (CGM) provides a continuous measure of interstitial glucose levels, a complete pattern of glucose excursions, real time alarms for thresholds and prediction of hypo and hyperglycaemia as well as rate of change alarms for rapid glycaemic excursions. For CGM users, there is a significant improvement in blood glucose control without increasing the risk of hypoglycaemia.

For people with type 1 diabetes using either multiple daily injections (MDI) or insulin pumps, CGM is very useful in improving glycaemic control without increasing the risks of severe hypoglycemia.1, 2

In the STAR 3 study, wherein 485 subjects switched from MDI and routine blood glucose testing to CGM, there was a significant improvement in HbA1c without an increase in frequency of severe hypoglycaemia or diabetes ketoacidosis (DKA) in both adults and children.3

CGM use has also been effective in other settings such as ICU (to maintain acceptable blood glucose
targets for critically ill patients);4,5 infants (having cardiorespiratory bypass surgery);6 newborn infants at risk for neonatal hypoglycemia;7 patients with cystic fibrosis who are at risk of developing cystic fibrosis related diabetes (CFRD);8 and monitoring patients with glycogen storage disorders specifically when combined with urine ketone and/or blood lactate measurements.9

For CGM users, there is a significant improvement in blood glucose control without increasing the risk of hypoglycaemia

In resource limited settings, where access to diagnosis, monitoring and treatment is a challenge,10 the use of CGM has its own limitations where the practical issues may result in these devices being more of a burden than a benefit.
From the perspective of the person with type 1 or type 2 diabetes, major barriers are awareness, cost, supply of usable equipment and technology. There is evidence that many people with diabetes reduce their frequency of self-monitoring of blood glucose (SMBG) after starting on CGM.11 This is contrary to what is required i.e. SMBG should be used as the primary data measure for all insulin dosing decisions whilst CGM is used to monitor the glycaemic trends based on which dosing adjustments can be made. In addition, towards the end of sensor life, the accuracy of the device is questionable and thus SMBG is still a necessary measure at regular intervals to make treatment decisions, calibrate the device and confirm any unusual CGM values.12 On occasion, SMBG results may be inaccurate as compared to CGM results.13 This “double” testing further increases the costs and confuses people with diabetes who have limited awareness, education and predisposed to the information technology gap.

The other challenge for people with diabetes using CGM devices is the high and low glucose threshold alarms. Unless the interpretation of these alarms and their adjustments and settings are well known to the person, this can be one of the major reasons for discontinuation of use of CGM devices.12

From the physician and healthcare provider perspective, major barriers include training, indirect costs (related to time required to download the data, its interpretation and face to face time with the patients) and support services (education, communications).

In an environment where the majority of people with diabetes have limited access to even basic commodities such as insulin, syringes, monitoring devices and education, the introduction of CGM devices is still a distant dream except for the privileged few. In many circumstances, insulin is used for sheer survival rather than adequate blood glucose control.

By Kaushik Ramaiya

Kaushik Ramaiya is a Consultant Physician and Assistant Medical Administrator at Shree Hindu Mandal Hospital in Dar es Salaam, Tanzania, and a member of the Diabetes Voice Advisory Board.

References

1. 

Hirsch IB, Abelseth J, Bode BW, et al. Sensor-augmented insulin pump therapy: results of the first randomized treat-to-target study. Diabetes Technol Ther 2008; 10:377–83.

2. Tamborlane WV, Beck RW, Bode BW, et al. Continuous glucose monitoring and intensive treatment of type 1 diabetes. N Engl J Med 2008; 359:1464–76.

3. Bergenstal RM, Tamborlane WV, Ahmann A ,et al. Effectiveness of sensor-augmented insulin-pump therapy in type 1 diabetes. N Engl J Med 2010; 363:311–20.

4. Finfer S, Chittock DR, Su S, et al. Intensive vs conventional glucose control in critically ill patients. N Engl J Med 2009; 360:1283–97.

5. Holzinger U, Warszawska J, Kitzberger R, et al. Real-time continuous glucose monitoring in critically ill patients: a prospective randomized trial. Diabetes Care 2010; 33:467–72.

6. Agus MS, Steil GM, Wypij D, et al. Tight glycemic control vs standard care after pediatric cardiac surgery. N Engl J Med 2012;367:1208–19.

7. Harris DL, Battin MR, Weston PJ, et al. Continuous glucose monitoring in newborn babies at risk of hypoglycemia. J Pediatr 2010;157:198–202. e1.

8. Schiaffini R, Brufani C, Russo B, et al. Abnormal glucose tolerance in children with cystic fibrosis: the predictive role of continuous glucose monitoring system. Eur J Endocrinol 2010; 162:705–10.

9.

White FJ, Jones SA. The use of continuous glucose monitoring in the practical management of glycogen storage disorders. J Inherit Metab Dis 2011; 34:631–42.

10.  Beran D, Yudkin JS & de Courten M. Access to care for patients with insulin requiring diabetes in developing countries: case studies of Mozambique and Zambia. Diabetes Care 2005; 28: 2136–2140.

11.  Diabetes Researchin Children Network (DirecNet) StudyGroup. Continuous glucose monitoring in children with type 1 diabetes. J Pediatr 2007; 151:388-93.

12. Gilliam LK, Hirsch IB: Practical Aspects of Real-Time Continuous Glucose Monitoring. Diabetes Technol Ther 2009; 11: 76-82.

13. Hirsch IB, Bode BW, Childs BP, et al. Self-monitoring of blood glucose in insulin and non-insulin using adults with diabetes: consensus recommendations for improving SMBG accuracy, utilization, and research. Diabetes Technol Ther 2008; 419-39.
Source: Diabetes Voice, March 2015
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