Effects of unrestricted access to flash glucose monitoring in type 1 diabetes

Rebound Hypoglycemia and Hyperglycemia in Type 1 Diabetes

AIMS

The aim was to investigate rebound hypoglycemic and hyperglycemic events, and describe their relation to other glycemic metrics.

METHODS

Data from intermittently scanned continuous glucose monitoring were downloaded for 90 days for 159 persons with type 1 diabetes. A hypoglycemic event was defined as glucose <3.9 mmol/l for at least two 15-minute periods. Rebound hypoglycemia (Rhypo) was a hypoglycemic event preceded by glucose >10.0 mmol/l within 120 minutes and rebound hyperglycemia (Rhyper) was hypoglycemia followed by glucose >10.0 mmol/l within 120 minutes.

RESULTS

A total of 10 977 hypoglycemic events were identified of which 3232 (29%) were Rhypo and 3653 (33%) were Rhyper, corresponding to a median frequency of 10.1, 2.5, and 3.0 events per person/14 days. For 1267 (12%) of the cases, Rhypo and Rhyper coexisted. The mean peak glucose was 13.0 ± 1.6 mmol/l before Rhypo; 12.8 ± 1.1 mmol/l in Rhyper. The frequency of Rhyper was significantly (P < .001) correlated with Rhypo (Spearman's rho 0.84), glucose coefficient of variation (0.78), and time below range (0.69) but not with time above range (0.12, P = .13).

CONCLUSIONS

The strong correlation between Rhyper and Rhypo suggests an individual behavioral characteristic toward intensive correction of glucose excursions.

The Frequency of Intermittently Scanned Glucose and Diurnal Variation of Glycemic Metrics

BACKGROUND

The relation between the frequency of intermittently scanned continuous glucose monitoring (isCGM) and diurnal variation of time in range (TIR) and time below range (TBR) is unknown.

METHOD

A total of 163 persons with type 1 diabetes who used isCGM had glucose data for 60 days downloaded. Mean TIR and median TBR were calculated for 15-minute periods and presented for daytime and nighttime. The values for tertiles of scanning frequency were compared.

RESULTS

The 1st tertile (n = 53) of the population scanned <10 times; the 2nd tertile (n = 56) 10-13 times, and the 3rd tertile (n = 54) >13 per 24 hours. TIR (%, mean ± (SD)) increased significantly from the 1st to the 3rd scan tertile both during the day (43.8 ± 14.8, 52.0 ± 12.3, 62.1 ± 12.8) and the night (44.5 ± 17.3, 52.3 ± 18.5, 64.0 ± 13.9; P < .0001). In contrast, TBR (median, (IQR)) was not significantly associated with scan tertiles during daytime (3.5% (1.1-7.8), 4.4% (1.8-6.1), 3.5% (2.1-6.1); P = .85) or nighttime (3.8% (1.4-13.7), 5.0% (1.6-9.6), 5.7% (3.6-10.9); P = .24). In a multiple regression model, a 50% increase in 24-hour scanning frequency was associated with a 7.8 percentage point increase in TIR (95% CI, 5.6-10.0).

CONCLUSIONS

Increased scanning frequency was associated with a higher TIR both during daytime and nighttime with no change in TBR.

Variation of glucose time in range in type 1 diabetes

INTRODUCTION

The aim of the study was to assess the variation of glucose time in range (TIR) for persons with type 1 diabetes who perform intermittently scanned continuous glucose monitoring (isCGM).

METHODS

Glucose data for 8 weeks were analysed for 166 persons. TIR was calculated over four consecutive 2 weeks periods. Sixty-one of the persons had two downloads with an interval of >3 months.

RESULTS

A total of 140 individuals (84%) used multiple daily injection, and 26 (16%) used continuous insulin infusion. The within-individual standard deviation (SD) for TIR was 6.3% corresponding to 95% limits of agreement for the difference between two TIR values of ±17.6%. Mean TIR calculated from the first and last 2 weeks was 52.2 ± 17.1% and 53.7 ± 16.4%, respectively (difference 1.5%, SD of the difference 10.4%, p = .07). For persons with two downloads separated by months, the SD of the difference in TIR was 12.6%.

CONCLUSIONS

The 95% limit of agreement for TIR is vast for persons using isCGM. It is difficult to draw firm conclusions regarding systematic differences when individual TIR from 2 weeks are compared. This may not be valid for users of insulin pumps with closed-loop insulin delivery.

Validity of Danish public criteria for providing flash glucose monitoring to participants with type 1 diabetes-An explorative cohort study

INTRODUCTION

Flash glucose monitor (FGM) use is increasing. A set of Danish criteria for regulating the use has been released. We assessed their validity.

METHODS

Patients with type 1 diabetes attending our clinic were offered Freestyle Libre Sensor for 12 months and stratified into fulfilling the Danish regional criteria (RC+) or not (RC-). Primary endpoint was achieving individualized target HbA1c. Secondary endpoints were HbA1c reduction ≥5%, time in range (TIR), time below range (TBR), daily scans, change in median HbA1c, and noted experiences.

RESULTS

Two hundred seventy-eight participants were included. Forty-four participants met target HbA1c after 1 year. No difference between RC+ and RC- was observed (p = .136). Higher age was associated with probability to meet target HbA1c (RR = 3.15, [95% CI: 1.15, 8.62]) as was frequent scans (RR = 1.88, [95% CI: 0.99, 3.57]). One hundred twenty-three participants met an HbA1c reduction ≥5%, the majority represented in RC+ (p = .023). Higher baseline HbA1c was associated with a reduction of HbA1c ≥5% after 1 year (RR = 1.97, [95% CI: 1.40, 2.78]). There was no difference between RC+ and RC- in TIR, TBR, and daily scans. Positive experiences dominated from both participants and healthcare professionals. More positive experiences were noted from healthcare professionals in RC- (p = .003) but no difference in reported experiences among participants in RC+ and RC- (p = .880).

CONCLUSION

The Danish Regional Criteria seems not a valid tool for regulation of FGM. Participants of older age and participants with more frequent daily scans might benefit more from FGM.

Effectiveness of adding alarms to flash glucose monitoring in adults with type 1 diabetes under routine care

AIM

Whether glucose sensor alarms improve metabolic control and are accepted by individuals with diabetes is unclear. Here, we investigated whether switching from a standard flash glucose monitoring system (FGM1) to a system equipped with hypo- and hyperglycemia alarms (FGM2) improves glycemic control and psychological outcomes in adults with type 1 diabetes (T1D).

METHODS

Subjects with T1D and > 4% of time in hypoglycemia or > 40% of time in hyperglycemia were studied while wearing FGM1 (4 weeks) and after switching to FGM2 for 8 weeks. The primary endpoint was the change in time in range (TIR 70-180 mg/dl [3.9-10.0 mmol/L]) after 4 weeks of FGM2 use. Time below range (TBR), time above range (TAR), mean glucose, coefficient of variation (CV), sensor scans, treatment satisfaction, and hypoglycemia fear were secondary outcomes.

RESULTS

We included 38 subjects aged 33.7 ± 12.6 year. During 4 weeks of FGM2 use, TIR increased from 52.8 to 57.0% (p = 0.001), TBR decreased from 6.2 to 3.4% (p < 0.0001) as did time < 54 mg/dl (from 1.4 to 0.3%, p < 0.0001) and CV (from 39.6% to 36.1%, p < 0.0001). These changes were confirmed after 8 weeks of FGM2 use. Treatment satisfaction improved and fear of hypoglycemia decreased. Subjects who had > 4% of time in hypoglycemia at baseline showed the greatest improvements in glucose control and treatment satisfaction.

CONCLUSION

Switching from FGM1 to FGM2 improved TIR and treatment satisfaction and reduced fear of hypoglycemia. Participants who benefited most from switching from FGM1 to FGM2 were those prone to hypoglycemia.

Glycemic Metrics Derived From Intermittently Scanned Continuous Glucose Monitoring

BACKGROUND

Glucose data from intermittently scanned continuous glucose monitoring (isCGM) is a combination of scanned and imported glucose values. The present knowledge of glycemic metrics originate mostly from glucose data from real-time CGM sampled every five minutes with a lack of information derived from isCGM.

METHODS

Glucose data obtained with isCGM and hemoglobin A1c (HbA1c) were obtained from 169 patients with type 1 diabetes. Sixty-one patients had two observations with an interval of more than three months.

RESULTS

The best regression line of HbA1c against mean glucose was observed from 60 days prior to HbA_1c measurement as compared to 14, 30, and 90 days. The difference between HbA1c and estimated HbA1c (=glucose management indicator [GMI]) first observed correlated with the second observation (R2 0.61, P < .001). Time in range (TIR, glucose between 3.9 and 10 mmol/L) was significantly related to GMI (R2 0.87, P < .001). A TIR of 70% corresponded to a GMI of 6.8% (95% confidence interval, 6.3-7.4). The fraction of patients with the optimal combination of TIR >70% and time below range (TBR) <4% was 3.6%. The fraction of patients with TBR>4% was four times higher for those with high glycemic variability (coefficient of variation [CV] >36%) than for those with lower CV.

CONCLUSION

The individual difference between HbA1c and GMI was reproducible. High glycemic variability was related to increased TBR. A combination of TIR and TBR is suggested as a new composite quality indicator.

Marked Improvement in A1C Levels After Initiation of Intermittently Scanned Continuous Glucose Monitoring Is Maintained Over 4 Years in Patients With Type 1 Diabetes

OBJECTIVE

This study aimed to demonstrate the effectiveness of long-term use of intermittently scanned continuous glucose monitoring (isCGM) in adult patients with type 1 diabetes.

DESIGN AND METHODS

In this retrospective real-world study, 689 patients with type 1 diabetes who were >18 years of age and using isCGM were identified from the electronic patient records in North Karelia, Finland. A1C data were collected before and after the initiation of isCGM. The primary outcome was a change in the mean A1C over time after isCGM started.

RESULTS

The greatest reductions in the mean A1C levels were observed 6 months (-0.54% [-5.9 mmol/mol], P <0.001) and 12 months (-0.42% [-4.6 mmol/mol], P <0.001) after the initiation of isCGM. Reduction in A1C remained significant for 4 years, although the mean reduction in A1C was -0.18% (-2.05 mmol/mol) (P = 0.009) at 48 months compared with baseline. In a subgroup analysis, patients with a baseline A1C >9% (75 mmol/mol) benefited the most from initiation of isCGM (reduction -0.97% [-10.6 mmol/mol], P <0.001, at 12 months and -0.92% [-10.1 mmol/mol], P <0.001, at 48 months). Neither sex nor age at the start of isCGM were correlated with A1C reduction.

CONCLUSION

Use of isCGM improves A1C levels significantly in adult patients with type 1 diabetes. Significant reduction in A1C persisted over 4 years of use, although the effect diminished over time.