The importance of HbA1c and glucose variability in patients with type 1 and type 2 diabetes: outcome of continuous glucose monitoring (CGM)

Acta Diabetologica, 04/03/2012

Sartore G et al. – HbA1c levels identify states of sustained hyperglycemia and seem to be unaffected by hypoglycemic episodes or short–lived glucose spikes, consequently revealing shortcomings as a “gold standard” indicator of metabolic control. Glucose variability indicators describe the glucose profile of type 1 diabetic patients and identify any worsening glycemic control (typical of longstanding diabetes) more accurately than HbA1c tests.


  • The study involved 68 patients divided into 3 groups as follows: 35 patients had type 1 diabetes (group 1); 17 had type 2 diabetes and were taking multiple daily injections (MDI) of insulin (group 2); and 16 patients had type 2 diabetes treated with OHA and/or basal insulin (group 3).
  • The indicators were obtained over at least 48 h using a continuous glucose monitoring (CGM) system.
  • HbA1c levels were measured at the baseline and after CGM.


  • HbA1c correlated significantly with AG (r = 0.74), AUC PP (r = 0.69) and HBGI (r = 0.74), but only in type 1 diabetic patients.
  • Patients with longstanding disease and type 1 diabetes had a greater glucose variability, irrespective of their HbA1c levels.
  • Insulin therapy with MDI correlated strongly with HbA1c, but not with glucose variability.

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