. 2021 Apr 9;13:42. doi: 10.1186/s13098-021-00654-3

Table 2.

Effect of flash glucose monitoring use and scanning frequency on glycosylated hemoglobin (HBA1c) levels in real-world studies of patients with type 1 and type 2 diabetes

Study (population)	Effect of:	HbA1c (%)
Fokkert et al. [20] T1D, n = 1054; T2D, n = 223; Other, n = 88	Before vs. after FGMS use on estimated HbA1c	At baseline: 8.0% (95% CI 7.9–8.1) At 6 months: 7.6% (95% CI 7.5–7.7); P < 0.001 vs. baseline At 12 months: 7.6% (95% CI 7.6–7.7); P < 0.001 vs. baseline
Eeg-Olofsson et al. [21] T1D, n = 8316; T2D, n = 538	Before vs. after FGMS use on HbA1c (method of measurement not specified)	T1D: 8.1% at baseline. Mean change –0.33% (95% CI − 0.36 to − 0.31); P < 0.0001 T2D: 8.6% at baseline. Mean change –0.52% (95% CI − 0.63 to − 0.40); P < 0.0001
Evans et al. [22] Meta-analysis of 29 studies; n = 1723 with T1D or T2D	FGMS use on laboratory HbA1c	In adults at 2–4 months: mean change − 0.56% (95% CI − 0.76 to − 0.36) In children and adolescents at 2–4 months: mean change − 0.54% (95% CI − 0.84 to − 0.23)
Ish-Shalom et al. [23] T1D, n = 6; T2D, n = 25	FGMS use on HbA1c (method of measurement not specified)	In patients with HbA1c ≥ 7.5% At 8 weeks: mean change − 1.33 ± 0.29%; P < 0.0001 At 24 weeks: mean change − 1.21 ± 0.42%; P = 0.009
Dunn et al. [24] n > 50,000	↑ Scanning frequency on estimated HbA1c	Highest (48.1 scans/day) vs. lowest (4.4 scans/day) scan rate group: 6.7% (95% CI 6.7–6.8) vs. 8.0% (95% CI 7.9–8.0; P < 0.001
Gomez-Peralta et al. [26] n = 22,949	↑ Scanning frequency on estimated HbA1c	Highest (39.6 scans/day) vs. lowest (3.9 scans/day) scan rate group: 6.9% (95% CI 6.9–7.0) vs. 8.0% (95% CI 8.0–8.1); P < 0.001
Calliari et al. [27] Brazil: 17,691 readers and 147,166 sensors Worldwide: 688,640 readers and 7,329,052 sensors	↑ Scanning frequency on estimated HbA1c	Brazil: Highest (43.1 scans/day) vs. lowest (3.6 scans/day) scan rate group: 6.7% (95% CI 6.6–6.8) vs. 7.6% (95% CI 7.4–7.7); P < 0.01 Worldwide: Highest (37.8 scans/day) vs. lowest (3.4 scans/day) scan rate group: 6.7% (95% CI 6.7–6.7) vs. 8.1% (95% CI 8.1–8.2); P < 0.01

Study (population)

Effect of:

HbA1c (%)

Fokkert et al. [20]

T1D, n = 1054; T2D, n = 223; Other, n = 88

Before vs. after FGMS use on estimated HbA1c

At baseline: 8.0% (95% CI 7.9–8.1)

At 6 months: 7.6% (95% CI 7.5–7.7); P < 0.001 vs. baseline

At 12 months: 7.6% (95% CI 7.6–7.7); P < 0.001 vs. baseline

Eeg-Olofsson et al. [21]

T1D, n = 8316; T2D, n = 538

Before vs. after FGMS use on HbA1c (method of measurement not specified)

T1D: 8.1% at baseline. Mean change –0.33% (95% CI − 0.36 to − 0.31); P < 0.0001

T2D: 8.6% at baseline. Mean change –0.52% (95% CI − 0.63 to − 0.40); P < 0.0001

Evans et al. [22]

Meta-analysis of 29 studies; n = 1723 with T1D or T2D

FGMS use on laboratory HbA1c

In adults at 2–4 months: mean change − 0.56% (95% CI − 0.76 to − 0.36)

In children and adolescents at 2–4 months: mean change − 0.54% (95% CI − 0.84 to − 0.23)

Ish-Shalom et al. [23]

T1D, n = 6; T2D, n = 25

FGMS use on HbA1c (method of measurement not specified)

In patients with HbA1c ≥ 7.5%

At 8 weeks: mean change − 1.33 ± 0.29%; P < 0.0001

At 24 weeks: mean change − 1.21 ± 0.42%; P = 0.009

Dunn et al. [24]

n > 50,000

↑ Scanning frequency on estimated HbA1c

Highest (48.1 scans/day) vs. lowest (4.4 scans/day) scan rate group:

6.7% (95% CI 6.7–6.8) vs. 8.0% (95% CI 7.9–8.0; P < 0.001

Gomez-Peralta et al. [26]

n = 22,949

↑ Scanning frequency on estimated HbA1c

Highest (39.6 scans/day) vs. lowest (3.9 scans/day) scan rate group:

6.9% (95% CI 6.9–7.0) vs. 8.0% (95% CI 8.0–8.1); P < 0.001

Calliari et al. [27]

Brazil: 17,691 readers and 147,166 sensors

Worldwide: 688,640 readers and 7,329,052 sensors

↑ Scanning frequency on estimated HbA1c

Brazil: Highest (43.1 scans/day) vs. lowest (3.6 scans/day) scan rate group:

6.7% (95% CI 6.6–6.8) vs. 7.6% (95% CI 7.4–7.7); P < 0.01

Worldwide: Highest (37.8 scans/day) vs. lowest (3.4 scans/day) scan rate group:

6.7% (95% CI 6.7–6.7) vs. 8.1% (95% CI 8.1–8.2); P < 0.01

BG levels are presented as mg/dL, which can be converted to mmol/L by multiplying values by 0.05551

BG blood glucose, FGMS flash glucose monitoring system, HbA1c glycosylated haemoglobin, T1D type 1 diabetes, T2D type 2 diabetes

↑ indicates increased