Longitudinal association between medication adherence and glycaemic control in Type 2 diabetes

Diabet Med. 2013 Mar;30(3):338-44. doi: 10.1111/dme.12046.


Aim: Despite the widespread assumption that adherence drives glycaemic control, there is little published support for this in Type 2 diabetes. The study objective was to determine whether self-reported medication adherence predicts future glycaemic control in Type 2 diabetes, after accounting for baseline control.

Methods: Medication adherence (4-item Morisky scale), glycaemic control (HbA(1c)%), and other variables were assessed in 287 adult primary care patients prescribed oral medication (40% also on insulin) for Type 2 diabetes. Glycaemic control was reassessed 6 months later. Regression analyses examined concurrent and future glycaemic control as a function of baseline medication adherence after adjustment for baseline glycaemia and other potential confounders.

Results: Only half of patients reported high adherence. Cross-sectional adjusted analysis replicated prior reports of an adherence-HbA(1c) association (P = 0.011). Even after adjusting for baseline HbA(1c), each one-point increase in baseline Morisky total score was associated with a 1.8 mmol/mol (or 0.16%) increase in HbA(1c) measured 6 months later. Additionally, baseline endorsement of forgetting to take medication was associated with a 4.7 mmol/mol (or 0.43%) increase in 6-month HbA(1c) (P = 0.005). This effect persisted after adjusting for psychological distress and did not vary by key demographic and medical features.

Conclusions: Even after stringent adjustment for baseline glycaemic control, self-reported adherence to diabetes medication predicts long-term glycaemic control. The Morisky scale is an easy-to-use clinical tool to identify patients whose glycaemic control will subsequently worsen, regardless of age, gender and psychological distress.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Blood Glucose / metabolism
  • Cross-Sectional Studies
  • Diabetes Mellitus, Type 2 / blood
  • Diabetes Mellitus, Type 2 / drug therapy*
  • Female
  • Glycated Hemoglobin / metabolism*
  • Humans
  • Hypoglycemic Agents / administration & dosage
  • Insulin / administration & dosage
  • Longitudinal Studies
  • Male
  • Medication Adherence*
  • Middle Aged
  • Self Report
  • Sex Factors


  • Blood Glucose
  • Glycated Hemoglobin A
  • Hypoglycemic Agents
  • Insulin