Continuous glucose monitoring detected hypoglycaemia in the Treating to Target in Type 2 Diabetes Trial (4-T)

Diabetes Res Clin Pract. 2017 Sep;131:161-168. doi: 10.1016/j.diabres.2017.01.022. Epub 2017 Mar 21.


Aims: Hypoglycaemia is a significant risk in insulin treated type 2 diabetes and has been associated with future risk of cardiovascular events. We compared the frequency of low-glucose events using continuous glucose monitoring (CGM) with that of self-reported hypoglycemic events at the end of the first and third years of the Treating to Target in Type 2 Diabetes Trial (4-T), which compared biphasic, prandial and basal insulin regimens added to sulfonylurea and metformin.

Methods: CGM using a Medtronic Gold system was performed in a subgroup of 4-T participants. CGM detected low-glucose events were defined at thresholds of ≤3.0 (CGM3.0) and ≤2.2 (CGM2.2) mmol/l.

Results: Of the 110 participants, 106 and 70 had CGM analysable data at the end of years 1 and 3 respectively. In both years, the frequency of CGM detected low glucose events was several fold higher than that of self-reported hypoglycaemia (symptoms with blood glucose less than 3.1mmol/l [<56mg/dl]). At the end of the first year, CGM3.0 and CGM2.2 mean (95%CI) event frequencies, expressed at events per participant per year, were 120 (85, 155) and 41 (21, 61) compared with 17 (8, 29) self-reported events during CGM, each p=0.001. The disparity at the end of the third year was similar.

Conclusions: These data demonstrate the likely under-reporting of hypoglycaemia and of potential hypoglycaemia unawareness in clinical trials. The clinical implications of these findings need to be explored further (ISRCTN No ISRCTN51125379).

Keywords: Clinical trials; Continuous glucose monitoring; Hypoglycaemia; Insulin therapy; Type 2 diabetes.

MeSH terms

  • Blood Glucose / metabolism*
  • Blood Glucose Self-Monitoring / methods*
  • Diabetes Mellitus, Type 1 / blood
  • Diabetes Mellitus, Type 2 / blood*
  • Female
  • Humans
  • Hypoglycemia / diagnosis*
  • Hypoglycemia / drug therapy
  • Hypoglycemic Agents / therapeutic use
  • Insulin / therapeutic use*
  • Male
  • Middle Aged


  • Blood Glucose
  • Hypoglycemic Agents
  • Insulin