Continuous Glucose Monitoring System Improves Blood Sugar Control in Type 1 Diabetes Interview with:
Dr Marcus Lind

Associate Professor of Diabetology at the University of Gothenburg
Gothenburg, Sweden
Chief Physician of Diabetology, Uddevalla Hospital
Uddevalla, Sweden What is the background for this study?

Response: This was a randomized trial over 16 months (cross-over study with 26 weeks of each treatment and a between wash-out period of 17 weeks) of 161 persons with type 1 diabetes. The main purpose was to evaluate whether a “diabetes tool”, denoted continuous glucose monitoring improves the glycaemic control, known to be essential to lower risks for diabetic complications such as injuries on eyes, kidneys, nerves and the cardiovascular system. The study also evaluated whether the glucose could be stabalised, i.e. having less fluctutations (beside the average level per se) and whether well-being, treatment satisfaction and feeling more confident in the daily living to avoid low glucose values which lead influence the cognitive function and can lead to unconciousness. Earlier trials exist of this therapy in connection to insulin pumps. But it has not been tested in randomized trials with persons only using multiple daily insulin injections to administer insulin which is the most common therapy among adults with type 1 diabetes.

Another novelty is that the current CGM-system (DexCom G4) has earlier shown a high accuracy and positive treatment experience among persons with type 1 diabetes, but it has not been tested in long-term randomized trials. Of note this trial was performed among adults with type 1 diabetes.

Continuous glucose monitoring (CGM) is a system where the patient has a sensor subcutaneously that he/she easily can change every week. It estimates the glucose level every minute and shows values on a hand-held small monitor (size of a small cell-phone) and whether the glucose levels are rising or declining. The hypothesis with the study is that if the patient has continuous information of the glucose level and trends it will improve treatment variables. The comparison group was that patients got information of their glucose control via capillary finger sticks which has been the general treatment for a long time period but can only be made at certain occasions since a procedure where blood must be taken from the finger tips. What are the main findings?

Response: The trial showed that the glycaemic control, measured by HbA1c, was reduced by 0.43%. It should be noticed that HbA1c is a measure of the mean glycaemic control and that the unit is %. Based on earlier studies it is believed that such a reduction has a meaningful role in reducing the risk of diabetic complications. Further, the glycaemic variability measured by two different variables (standard deviation and mean amplitude of glycaemic excursions) was lower during CGM therapy. From earlier literature there are indications that lower glycaemic variability besides the average glucose level per se is beneficial for avoiding diabetic complications. Well-being, treatment satisfaction and confidence regarding hypoglycaemia (too low glucose levels) were also improved by CGM.

Regarding adverse effects, which also is an essential part of clinical trials of novel therapies, there were no indications of any “harmful” effects of the treatment. The time with low glucose levels was measured and was on average 40 minutes per each 24h period with  continuous glucose monitoring  and 69 minutes with conventional therapy. One person with CGM and 5 with conventional therapy had severe hypoglycaemia, i.e. so low glucose levels that they became unconscious or needed assistance to solve the situation by another person. All adverse effects (AE) were registered during the study and there were no obvious differences in other AEs for treatments.

In summary, among persons with type 1 diabetes treated with multiple daily insulin injections  continuous glucose monitoring (DexCom G4) improves glycaemic control and reduces glycaemic variability. It improves well-being and increases treatment satisfaction and the patient gets more confident regarding low glucose levels. What should readers take away from your report?

Response: -That CGM is a treatment option that they should test if they have the possibility. Few treatment options exist in the type 1 diabetes field. In type 2 diabetes many different drugs have emerged during the last decades, and it is therefore important to test the treatment alternatives that exist for persons with type 1 diabetes. In general in medicine, no treatment fits all patients. But I believe most patients will appreciate CGM and facilitate the glucose control. But since it is a disease in the daily living I believe one should else just test the therapy during a period and If not satisfied one can simply switch back to regular capillary testing. If improving glycaemic control, we know from other studies that it will reduce the risk of long-term diabetic complications. Hence, it is worth testing all treatment options available.

And as we found that patients improved their well-being and found on average higher treatment satisfaction it is also likely that a patient will like the treatment in the daily living. We had no indications that the treatment should be harmful in any sense which also is an essential aspect among novel treatments tested. We evaluated time with low glucose values, i.e. at levels when the cognitive function can be negatively influenced and in worst case lead to unconciousness. During CGM the average time per 24 hour period was 40 minutes and during regular therapy 69 minutes. 5 patients had severe hypoglycaemias (unconciousness or needing assistance to solve a hypoglycaemia) during regular therapy and 1 patient during CGM therapy. What recommendations do you have for future research as a result of this study?

Response: There are of course many interesting fields. One example. I believe various studies of how CGM best is used could be an interesting complement. It gives many possibilities in the future. E.g. that clinics could get detailed data regularly and assist the patient e.g. on phone or via other media in their daily living. To track and analyse CGM data. CGM gives a lot of data, each minute! And an essential question is how it could be best utilised by the patient and in collaboration with the doctor and diabetes educator. Possibly we could improve this and even “increase the effect. Is there anything else you would like to add?

Response: This was an investigator initiated trial. The manufacturer of the CGM-system (DexCom G4) that was tested had no role in the design or carrying out the trial. However, the NU-Hospital group who acted as sponsor received CGM-system and sensors free of charge for the study from the manufacturer (DexCom Corp.) and financial support . The study was carried out at 15 sites in Sweden and most costs at sites such as salaries were covered locally by sites. Thank you for your contribution to the community.


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Beck RW, Riddlesworth T, Ruedy K, Ahmann A, Bergenstal R, Haller S, Kollman C, Kruger D, McGill JB, Polonsky W, Toschi E, Wolpert H, Price D, for the DIAMOND Study Group. Effect of Continuous Glucose Monitoring on Glycemic Control in Adults With Type 1 Diabetes Using Insulin InjectionsThe DIAMOND Randomized Clinical Trial. JAMA. 2017;317(4):371-378. doi:10.1001/jama.2016.19975

Davidson MB. Continuous Glucose Monitoring in Patients With Type 1 Diabetes Taking Insulin Injections. JAMA. 2017;317(4):363-364. doi:10.1001/jama.2016.20327

Note: Content is Not intended as medical advice. Please consult your health care provider regarding your specific medical condition and questions.

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Last Updated on January 24, 2017 by Marie Benz MD FAAD