Background: Glycemic control in patients with type 2 diabetes mellitus is a health care challenge. Although there are various recommendations for its prevention and management, no one solution has been identified to effectively prevent and manage its complications. Treatment recommendations for type 2 diabetes mellitus may include a single agent hypoglycemic medication or combinations of oral and injectable hypoglycemic medications with diet and exercise in an attempt to achieve optimal glucose control. Currently, there are no published systematic reviews specific to the intervention of exercise and diet in addition to hypoglycemic medication for the improvement of HbA1C in patients with type 2 diabetes mellitus. The objective of this systematic review was to synthesize evidence related to diet and exercise in adult patients with type 2 diabetes mellitus currently taking hypoglycemic medication to determine if management should include diet and exercise to improve glycemic control.
Objectives: To identify the best available evidence on the effectiveness of nutrition and exercise in addition to medication on HbA1C in patients with type 2 diabetes mellitus.
Inclusion criteria: Types of participants
Adults ages 18 years and older with type 2 diabetes mellitus, regardless of gender, ethnicity or national origin.
Types of intervention(s)/phenomena of interest
Exercise and/or nutritional programs for adult participants with type 2 diabetes mellitus treated with antihyperglycemic agents.
Types of studies
Randomized and pseudo-randomized control trials.
Types of outcomes
HbA1C
Search strategy: To find both published and unpublished studied in the English language from the inception of each database through September of 2013. A primary search of PubMed, CINAHL, EMBASE and the Cochrane Central Register of Controlled Trials were conducted using identified keywords and indexed terms across all included databases. A gray literature search was also performed.
Methodological quality: Two reviewers evaluated the included studies for methodological quality utilizing standardized critical appraisal instruments from the Joanna Briggs Institute.
Data collection and synthesis: Data were extracted using standardized data extraction instruments from the Joanna Briggs Institute. Due to clinical heterogeneity between included studies, statistical meta-analysis was not feasible. The results are presented in a narrative form.
Results: Four articles, three of which featured interventions utilizing exercise in addition to hypoglycemic medications, and one, a nutritional intervention, were chosen for inclusion in this review. Two of the exercise interventions and one nutritional intervention showed an improvement in HbA1C in patients with type 2 diabetes mellitus. The study with a nutritional intervention showed a reduction of HbA1C after six months compared to the control group (-0.4, p=0.007). One study that focused on exercise showed an improvement on HbA1C of 6.00 +/-0.83, p=0.008). A second study that focused on exercise intervention also demonstrated a small but not significant reduction of HbA1C after six months (8.9 +/-1.0 at baseline to 8.7 +/-1.1). A third study with an exercise intervention showed no effect in the HbA1C after 2 years (effect size 0, p=0.999).
Conclusions: A reduction in HbA1C in adults with type 2 diabetes may be seen with the addition of nutritional and/or exercise interventions on top of antihyperglycemic medications. The studies included in this review suggest that a supervised aerobic exercise program three times a week may improve outcomes.