Using CGM to improve glycaemic control

Until recently, HbA_1c and fingerprick “diaries” were the only way for people with type 1 or type 2 diabetes and their healthcare team to assess glycaemic control. Sometimes, however, information from HbA_1c and fingerprick tests is just not enough to adjust treatment effectively. 

Continuous glucose monitoring (CGM) systems can offer people with the condition and their healthcare professionals another option and a broader window to look into their diabetes control.

CGM: The Liverpool experience
Like all diabetes centres worldwide, we struggle to support some people with diabetes. Despite our best efforts and those of people with the condition – as well as multiple consultations – glycaemic control often remains sub-optimal, or fluctuations in blood glucose levels continue to cause distress. 

An opportunity arose within our diabetes centre to adopt CGM and use it as part of a care pathway for people with type 1 diabetes. This short article describes an audit of this process and its outcomes.

Aims of the clinical service audit
The main aim of this audit was to show that CGM system use can improve diabetes control in people with type 1 diabetes when standard blood glucose monitoring has failed, and to identify areas of hypo- and hyperglycaemia that previous blood glucose testing has missed.

Methodology
A care pathway and diet and lifestyle diary were developed to ensure continuity within the service and as an audit tool. This was discussed in detail with the person with diabetes and compared with the CGM graphs and blood glucose readings. Twelve people with type 1 diabetes on multi-dose insulin therapy completed the study. 

HbA_1c results taken at 3, 12, 24 and 36 months were then compared with the pre-CGM HbA_1c results.

Main results 
The information gained from the device showed in all people who had used it areas for improvement that would not have been seen with normal fingerprick testing, for example overnight blood glucose levels. 

Prior to CGM the mean HbA_1c level of participants was 8.8% (73 mmol/mol). After 3 months, mean HbA_1c levels had reduced significantly to 8.0% (64 mmol/mol; P=0.03). 

Mean HbA_1c levels at 12, 24 and 36 months were then compared with the pre-CGM HbA_1c results to see if improvements were maintained over time. Results are as follows:

• At 12 months, mean HbA_1c level was 8.2% (66 mmol/mol; P=0.005).
• At 24 months, mean HbA_1c level was 7.9% (63 mmol/mol; P=0.005).
• At 36 months, mean HbA_1c level was 7.5% (58 mmol/mol; P=0.002).

Conclusion
A mean reduction in HbA_1c of 1.3% was observed over the 3 years without significant increase in weight or insulin dosage. HbA_1c levels continued to improve after completion of the 3-month care pathway and participants went back to their pre-study care regimens. 

Although the study end-points were weight, insulin dose and HbA_1c level, it quickly became apparent when reviewing participants that reduction in hypoglycaemia and confidence in their blood glucose levels meant as much to them, if not more, than the reduction in HbA_1c level. Future audit of this service will therefore also include questionnaires on hypoglycaemia and quality of life. 

A full article discussing this audit, the use of CGM systems and evidence of their use in practice, how they work and some of the systems available, will be coming shortly.