Impact of metformin-induced gastrointestinal symptoms on quality of life and adherence in patients with type 2 diabetes.
OBJECTIVE
Gastrointestinal (GI) symptoms are common in patients with type 2 diabetes mellitus (T2DM). This study assesses the impact of 1) metformin on GI symptoms and health-related quality of life (HRQoL) and 2) metformin-associated GI symptoms on medication adherence in patients with type 2 diabetes newly beginning therapy.


METHODS
Patients with T2DM aged>or=18 years starting metformin from January to June 2007 who filled their prescriptions for >or=3 months were identified from a health benefits company database. Via telephone, GI symptom impact was evaluated in a 360-patient sample using the validated Bowel Symptom Questionnaire and Medical Outcomes Study 36-Item Short-Form Health (SF-36) survey. Adherence was assessed using the medication possession ratio (MPR). Logistic regression adjusting for demographic and clinical covariates was used to assess the relationship between GI symptoms and MPR<80%.


RESULTS
The most and least common GI symptoms reported were diarrhea (62.1%) and retching (21.1%), respectively. Most GI symptoms were associated with lower physical and mental HRQoL (P<0.05). Most changes in specific HRQoL reached the minimum important difference of 3 points. Bloating, nausea, and abdominal pain were significantly associated with MPR<80%. Adjustment for demographic, clinical, and HRQoL factors made these relationships less evident.


CONCLUSIONS
Metformin-associated GI symptoms in patients with T2DM lead to lower physical and mental HRQoL, which may result in patient nonadherence or physician reluctance to optimally titrate the metformin dose.
Florez
Hermes
H
University of Miami-Humana Health Service Research Center, Miami, FL 33125, USA. hflorez@med.miami.edu
Luo
Jiacong
J
Castillo-Florez
Sumaya
S
Mitsi
Georgia
G
Hanna
John
J
Tamariz
Leonardo
L
Palacio
Ana
A
Nagendran
Sukumar
S
Hagan
Michael
M
D000368:Aged; D016001:Confidence Intervals; D003625:Data Collection; D003924:Diabetes Mellitus, Type 2 / Q000188:drug therapy* / Q000523:psychology; D005260:Female; D005767:Gastrointestinal Diseases / Q000139:chemically induced* / Q000523:psychology; D006305:Health Status Indicators; D006801:Humans; D007004:Hypoglycemic Agents / Q000009:adverse effects* / Q000627:therapeutic use; D016015:Logistic Models; D008297:Male; D055118:Medication Adherence / Q000523:psychology; D008687:Metformin / Q000009:adverse effects* / Q000627:therapeutic use; D016017:Odds Ratio; D011594:Psychometrics; D011788:Quality of Life; D012307:Risk Factors; D011795:Surveys and Questionnaires; D014481:United States; D016903:Drug Monitoring
D007004:Hypoglycemic Agents; D008687:Metformin