Table 2

Summary of published data

SourceType 1, type 2, nondiabetesSubjects (n)Approximate HbA1c range (National Glycohemoglobin Standardization Program)Children, adultsLengthMethod: discrete or CGMCurve fit (R2)Predict HbA1c slope (95% CI)Intercept (mg/dL) (95% CI)Range of actual mean glucose at 6.9–7.1%
Discrete
 Hempe et al. (11)Type 1 diabetes1286.5–18.7%Children, adolescents, adultsUp to 2.3 yearsDiscreteLinear (0.50)18.5*∼−4.8*∼90–235
 Rohlfing et al. (12)Type 1 diabetes1,4395.3–13.3%Adolescents, adults3–9 yearsDiscrete 7 point quarterlyLinear (0.67)35.6−77.3∼100–250
 Makris et al. (13)Type 2 diabetes and/or metabolic syndrome1405.1–10.9%Adults 41–81 years1 monthDiscrete 6 point 12 times in a monthLinear (0.86)34.7 (32.5–37.0)−79.2∼127–207
CGM
 Nathan et al. (22)Type 1 and type 2 diabetes and nondiabetes15, 7, and 34.6–10.2%Adults3 monthsCGMLinear (0.79)31.5−68.6Too few
 Wilson et al. (16)Type 1 diabetes485.8–8.8%Children, adolescents6 monthsCGMLinear18 (14–22)+40∼138–189
 Nathan et al. (15)Type 1 and type 2 diabetes and nondiabetes268, 159, and 803.8–14.3%Adults3 monthsIntermittent CGM >7 days over 3 months discreteLinear (0.84)28.7−46.7∼125–205
 Mazze (14)Type 1 and type 2 diabetes and nondiabetes1244.9–10.4%Adults8–75 daysCGMLinear (0.71)26.3*−32.7*∼130–150
 Current studyType 1 diabetes2525.1–9.7%Children, adolescents, adults3-month continuousCGMLinear (0.63)24.4 (22.0−26.7)−16.2128–187
  • *Study originally reported slope from a model with HbA1c as the independent variable (i.e., HbA1c = slope × mean glucose + intercept). Values were converted to equivalent slope and intercept with mean glucose as the dependent variable using the reported R2 value.

  • †Estimated from graphs.