Table 3.
| Study | N | Patients | Methods | Primary outcome (HbA1C change unless otherwise noted) | Select secondary outcomes | Safety/other |
|---|---|---|---|---|---|---|
| EFFICACY: Adults with T1DM – HbA1C reduction | ||||||
| Beck et al.24 | 158 | Age ≥25 years (mean 48); HbA1C 7.5–9.9% (mean 8.6%); MDI | rtCGM (Dexcom G4) versus SMBG; 24 weeks | −0.6% (p<0.001) | Mean TTR: 736 versus 650 min/day; adjusted difference 77 (p=0.005) | Severe hypoglycaemia: 4.2 versus 12.2 events/100 person-years); 93% used rtCGM 6 days/week |
| Lind et al.25 | 161 | Age ≥18 years (mean 44 years); HbA1C ≥7.5% (mean 8.6%) | rtCGM (Dexcom G4) versus SMBG; crossover 26 weeks, 17-week washout | −0.43% (p<0.001) | Increased treatment satisfaction (DTSQ) with rtCGM, mean score increase 3.43 (p<0.001) | Hypoglycaemia: 1 (0.6%) versus 5 (3.3%) |
| Sequeira et al.26 | 25 | Age ≥18 years (mean 40 years); mean HbA1C 8.5%; 76% Latinx, uninsured; MDI | rtCGM (Dexcom G7) versus SMBG; crossover; 28 weeks, no washout | Not SS | TTR: no SS difference; 80% of participants wanted to continue using CGM, felt insulin adjustment was easier, felt CGM prevented hypoglycaemia | Hypoglycaemia: no SS difference |
| Tumminia et al.27 | 20 | Age 18–60 years (mean 34 years); A1C ≥8% (mean 8.7%); MDI or CSII; analysed n=14 used sensor ≥40% of time | rtCGM (Medtronic Guardian REAL-Time) versus SMBG; crossover; 24 weeks, 2-week washout | Mean HbA1C decreased from 8.5% to 7.8% (p<0.05) with rtCGM | Risk of hyperglycaemia reduced (p<0.05) with rtCGM; MDI subgroup had further decreased risk of hyperglycaemia and hypoglycaemia (p<0.05) | No severe hypoglycaemia; risk of hypoglycaemia reduced (p<0.05) |
| Visser et al.28 | 254 | Age ≥18 years (mean 43 years); T1DM; HbA1C ≤10% (mean 7.4%); MDI or CSII; isCGM use for at least 6 months (median use >2 years); median scans per day: 11 | rtCGM (Dexcom G6) versus isCGM (FreeStyle Libre); 6 months | Mean TTR higher with rtCGM (59.6% versus 51.9%; mean difference 6.85%; p<0.0001) | HbA1C further decreased with rtCGM (7.1% versus 7.4%; p<0.0001); fear of hypoglycaemia (survey) decreased with rtCGM (mean difference −2.62 points; p=0.0071) | Mean time spent in severe hypoglycaemia: 0.47% versus 0.84% (p=0.007); bleeding with sensor insertion in rtCGM group only (9%); skin reaction more common in isCGM group (7% versus 13%) |
| EFFICACY: Young people with T1DM – HbA1C reduction or TTR | ||||||
| Boucher et al.29 | 64 | Age 13–20 years (mean 16 years); HbA1C ≥9% (mean 10.9%) | isCGM (Freestyle Libre) versus SMBG; 24 weeks | −0.2%, (p=0.576) not SS | isCGM group checked glucose 3.2 times more than SMBG group (p<0.001); improved diabetes treatment satisfaction (DTSQ) difference between groups 0.47 (p=0.048) | No severe hypoglycaemia events; no SS difference in DKA (18% versus 16%) |
| Laffel et al.30 | 153 | Age 14–24 years (mean 17 years); HbA1C 7.5–10.9% (mean 8.9%); 38% non-white; 41% public insurance | rtCGM (Dexcom G5) versus SMBG; 26 weeks | −0.37% (p<0.01) | TTR: 43% versus 35%, (p<0.001); mean time in hypoglycaemia was lower with rtCGM (−0.7%; p=0.002) | Severe hypoglycaemia: 8.3 versus 7.8 events/100 person-years); DKA: 8.3 versus 2.6 events/100 person-years) |
| Thabit, et al.31 | 31 | Age 16–24 years (mean 21 years); HbA1C ≥7.5% (mean 9.3%) | rtCGM (Dexcom G6) versus SMBG; crossover; 8 weeks, 3–4-week washout | Higher TTR with rtCGM mean difference 11.1% (p<0.001) | HbA1C reduction: −0.76% (p<0.001) | No SS difference in hypoglycaemia; 84% sensor usage |
| EFFICACY: Adults with T2DM – HbA1C reduction | ||||||
| Beck et al.32 | 158 | Age ≥25 years (mean 60 years); HbA1C 7.7–9.9% (mean 8.5%); EGFR ≥45 mL/min/1.73 m2; 46% non-white (CGM group), 27% (SMBG group) | rtCGM (Dexcom G4) versus SMBG; 24 weeks | −0.3 (p=0.022) | TTR (median) increased further with rtCGM (802–882 min/day versus 794 to 836 min/day); no SS difference in glucose variability | No severe hypoglycaemia; no SS difference in time in hypoglycaemic range; mean rtCGM use: 6.7 days/week |
| Ehrhardt et al.33 | 100 | Age ≥18 years (mean 57.7 years); HbA1C 7–11.9% (mean 8.3%); not on prandial insulin; rtCGM group slightly younger, more men | rtCGM (Dexcom SEVEN) versus SMBG; 12 weeks; 4 cycles of 2 weeks on/1 week off | −0.6 (p=0.002) | New basal insulin starts: 6% versus 16%; net medication/dose changes similar between groups | Hypoglycaemia: not available |
| Haak et al.34 | 224 | Age ≥18 years (mean 59 years); HbA1C 7.5–12% (mean 8.7%); MDI or prandial only (95%), CSII (5%) | isCGM (Freestyle Libre) versus SMBG; randomized 2:1; 6 months | −0.03, not SS (p=0.822) Age <65 years: −0.53% (p=0.03) |
TTR: no difference; higher mean DTSQ satisfaction score with isCGM (13.1 versus 9; p<0.0001) | Severe hypoglycaemia: 2% versus 1%; isCGM decrease time in hypoglycaemia by 43% (p=0.0006) |
| Martens et al.35 | 175 | Age ≥30 years (mean 57 years); HbA1C 7.8–11.5% (mean 9.1%); primary care; on basal insulin, other agents, no prandial insulin; 53% ethnic minorities | rtCGM (Dexcom G6) versus SMBG; randomized 2:1; 8 months | −0.4% (p=0.02) | TTR: 59% versus 43%, adjusted difference 15% (p<0.001); mean time glucose >250 mg/dL: 11% versus 27%, adjusted difference 16% (p<0.001) | Severe hypoglycaemia: 1% versus 2%; median rtCGM use: 6.1 days/week |
| Grace et al.37 | 38 | Adults (mean age 55 years); HbA1C >7.5% (mean 10.1%); on various therapies – excluding prandial insulin; basal insulin (42%), non-insulin injectable (24%), oral diabetes medication, i.e. metformin (55%), sulfonylurea (39%) and/or diet/exercise regimen | rtCGM (Dexcom G6) – single arm/no comparator group; open-label, interventional, cohort study; 6 months | −3.0% (p<0.01) | TTR: increased from 57% to 72.2% (mean change 15.2; p<0.001); body weight: mean change of −3.1 kg (p=0.002) Subgroup with 0–1 medications (n=13) showed further improvement in TTR (mean change 17.6; p=0.002) |
No severe hypoglycaemia; therapy intensified: 53% of patients; medication changes or reduction: 39% |
| EFFICACY: Special populations – type 1 or 2 diabetes | ||||||
| Ruedy et al.39 | 116 | Older adults, age ≥60 years (mean 67 years); T1DM (29%) or T2DM (71%); HbA1C 7.5–10% (mean 8.5%) | rtCGM (Dexcom G4) versus SMBG; 24 weeks | −0.4% (p<0.001) | TTR: CGM group: increased from 796 to 889 min/day; control group: decreased from 753 to 732 min/day (p<0.001) | No severe hypoglycaemia; 97% used rtCGM 6 days/week |
| Joubert et al.40 | 15 | Haemodialysis 3x/week; −age 18–80 years (mean 61 years); mean HbA1C 6.9%; T1DM (n=2), T2DM (n=9), or secondary DM; 20% managed with diet only | rtCGM (Medtronic iPro2) versus SMBG; 6 weeks with SMBG, 6 weeks with blinded CGM (5 day recording every 2 weeks) | HbA1C decreased from 6.9% to 6.5% (p<0.05); mean glucose decreased from 150 to 139 mg/dL (p<0.05) | Treatment changes occurred more often with rtCGM (2.1 versus 1.4; p<0.05); mean glucose lower on dialysis days (137 versus 141 mg/dL; p<0.05) | No SS difference in hypoglycaemia |
| EFFICACY and SAFETY – Pregnant – T1DM, T2DM or GDM – HbA1C reduction | ||||||
| Feig et al.41 | 325 | Age 18–40 years; T1DM, MDI or CSII; pregnant (66%): HbA1C 6.5–10% (mean 6.8%), mean age 31 years; planning pregnancy (34%): HbA1C 7–10% (mean 7.5%), mean age 33 years | rtCGM (Guardian RT or MiniMed Minilink) versus SMBG; pregnant: 34 weeks; planning pregnancy: 24 weeks | −0.19% (p=0.0207) if pregnant; no SS difference in planning pregnancy subgroup | TTR: pregnant: 68% versus 61% (p=0.0034) | Severe hypoglycaemia: 3% versus 4% (p=0.10) not SS; LGA: OR 0.51 (95% CI: 0.28–0.90; p=0.0210); neonatal ICU stay >24 hours: OR 0.48 (95% CI: 0.26–0.86; p=0.0157); neonatal hypoglycaemia: OR 0.45 (95% CI: 0.22–0.89; p=0.0250) |
| Secher et al.42 | 154 | T1DM (80%), T2DM (20%); adult women (mean age 31); median HbA1C 6.7%; MDI or CSII | rtCGM (Medtronic Guardian RT) versus SMBG; rtCGM use × 6 days at weeks 8, 12, 21, 27 and 33 | No difference in HbA1C | TTR: no difference | Severe hypoglycaemia: no difference (16% in both); no difference in LGA, preterm delivery, or severe neonatal hypoglycaemia |
| Wei et al.43 | 106 | Adult women with GDM at 24–28 weeks; mean HbA1C 5.8% | rtCGM (Medtronic Gold) versus SMBG; subgroups: early CGM (worn second trimester), late CGM (worn third trimester) | No SS difference in HbA1C | Excessive gestational weight gain decreased: 33.3% versus 56.4% (p=0.039); early rtCGM subgroup (second trimester) gained less weight: 12.7 versus 14.3 kg (p=0.017) | No differences in neonatal outcomes (LGA, neonatal hypoglycaemia, macrosomia) |
| SAFETY – T1DM | ||||||
| Bolinder et al.44 | 328 | Age ≥18 years (mean 44 years); T1DM; HbA1C ≤7.5% (mean 6.7%); MDI or CSII | isCGM (Freestyle Libre) versus SMBG; 6 months | Time in hypoglycaemia decreased: −1.24 h/day (p<0.0001), 38% reduction | Difference between groups with DTSQ score: 6.1 (p<0.0001) | Severe hypoglycaemia: similar between groups |
| Heinemann et al.45 | 149 | Age ≥18 years (mean 47 years); T1DM; HbA1C ≥9% (mean 7.5%); MDI; severe hypoglycaemia in the past 12 months (requiring assistance) or impaired hypoglycaemia awareness | rtCGM (Dexcom G5) versus SMBG; 26 weeks | Mean number of hypoglycaemia events/28 days, IRR 0.28 (p<0.0001); incidence of hypoglycaemia decreased 72% | Lower glucose variability: CV decreased from 39.3% to 34.1% (p<0.0001) | Severe hypoglycaemia: 0.64 versus 1.18 events/patient-year; IRR 0.36 (p=0.0247): 64% decrease in severe hypoglycaemia |
| Olafsdottir et al.46 | 161 | Age ≥18 years (mean 45 years); T1DM; HbA1C ≥7.5% (mean 8.7%); MDI | rtCGM (Dexcom G4) versus SMBG; crossover; 26 weeks, 17-week washout | Decreased time spent in nocturnal hypoglycaemia: 2.63% versus 4.74%; mean difference −2.11 (p<0.001) | Decreased time spent in daytime hypoglycaemia: 2.81% versus 4.77%; mean difference −1.93 (p<0.001); lower glucose variability: CV 0.37 versus 0.40): difference −0.03 (p<0.001) | Severe hypoglycaemia occurred less often (1 versus 5) |
| Pratley et al.47 | 203 | Age ≥60 years (median 68 years); T1DM; HbA1C <10% (mean 7.5%); MDI or CSII | rtCGM (Dexcom G5) versus SMBG; 6 months | Time in hypoglycaemia decreased; −1.9% (p<0.001) | Lower glucose variability: CV decreased from 41% to 37% (−4.7%; p<0.001) | Severe hypoglycaemia: 1.9 versus 22.4 events/100 person-years |
CGM, continuous glucose monitor; CSII, continuous subcutaneous insulin infusion; CV, coefficient of variation; DKA, diabetic ketoacidosis; DM, diabetes mellitus; DTSQ, Diabetes Treatment Satisfaction Questionnaire; GDM, gestational diabetes mellitus; IRR, incidence rate ratio; IS, intermittently scanned; LGA, large for gestational age; MDI, multiple daily injections; OR, odds ratio; RT, real time; SMBG, self-monitoring blood glucose; SS, statistically significant; TTR, time in target range blood glucose 70–180 mg/dL; T1DM, type 1 diabetes mellitus; T2DM, type 2 diabetes mellitus.
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