ISSUE OF PUBLIC HEALTH: TYPE II DIABETES
Diabetes is a significant problem in places like the United States, particularly type II diabetes. Type II diabetes is often associated with obesity and poor lifestyle choices, although genetic predisposition also seems to play a role in the development of the disease (Look AHEAD Research Group, 2013). The three studies chosen for discussion here are all studies that examine the impact of diet and lifestyle choices on people who have type II diabetes; many of these researchers are interested in developing methods to offset the significant health risks and population-wide costs of such high prevalence of the disease.
The research papers were chosen using a number of important criteria. First, the papers had to come from a reputable source; each of the papers was chosen from a reputable medical or scientific journal. None of the papers were published earlier than the year 2000. Although the earliest paper discussed in this text was written in 2003—nearly 13 years ago—it is one of the foundational studies for many of the other studies done on the impact of metformin on the incidence of diabetes type II.
Although each of these articles were published in the New England Journal of Medicine, this is more of a coincidence than a conscious choice; however, this journal is quite a reputable one, and the research published in this journal is generally accurate and thoroughly investigated. Each of the three articles discuss the importance of behavioral factors on the development and the prevention of diabetes mellitus type II, and each also discusses potential interventions that might be effective for individuals who have presented with this particular disease (Diabetes Prevention Program Research Group, 2003; Look AHEAD Research Group, 2013; Rejeski et al., 2012). All of these articles were also chosen because the research was conducted by a group of researchers—the scale of each study was quite large.
Description
Exposure, Intervention: Researchers were testing the outcome of exposure to diet and lifestyle changes as well as metformin on adults at high risk for type II diabetes.
Outcome: Lifestyle changes and treatment with the drug metformin kept high-risk adult individuals from developing diabetes.
Main Result
What was the exposure or intervention? The intervention was metformin treatment or diet and lifestyle modifications.
What was the outcome? Both groups showed lower rates of diabetes development, but the diet and lifestyle change group showed a lower incidence of diabetes after the study.
What was the study design? The researchers carried out a double-blind study with a placebo control group.
What was the study population? The study population was 3234 non-diabetic adults who were at high risk for diabetes.
What was the main result? Lifestyle changes and treatment with the drug metformin kept high-risk adult individuals from developing diabetes.
Internal Validity
Are the results likely to be affected by observation bias? The results are unlikely to be tainted by observation bias, as the researchers followed the groups closely for 2-5 years, and tracked annual glucose tolerance level, which is not subjective.
Are the results likely to be affected by recall bias? This is highly unlikely, unless participants were underreporting their deviations from diet and lifestyle changes. However, that is the group that showed the most improvement overall.
Are the results likely to be affected by confounding? It is possible, but unlikely. Results of the study were closely linked to scientific measurements.
Generalizability: External validity
Can the study results be applied to the eligible population? Yes. This was a large-scale study and recommending diet changes and exercise to the at-risk population is generally acceptable.
Can the study results be applied to the source population? Yes, the researchers demonstrated a link between lowered risk of diabetes and diet and exercise changes.
Can the study results be applied to other relevant populations? Yes, particularly young, overweight children who eat unhealthy foods and have problems with borderline type II diabetes.
Study 2: Cardiovascular effects of intensive lifestyle intervention in type 2 diabetes
Description
Exposure, Intervention: The research investigated the effect of lifestyle intervention—not merely lifestyle change—on individuals who have type II diabetes.
Outcome: The research demonstrated that lifestyle intervention did not reduce the likelihood of cardiovascular events in individuals with diabetes.
Main Result
What was the exposure or intervention? The intervention was lifestyle management and intervention on individuals who have type II diabetes.
What was the outcome? The research demonstrated that lifestyle intervention did not reduce the likelihood of cardiac events in individuals with diabetes.
What was the study design? The study was a double-blind study at different diabetes research centers around the United States.
What was the study population? The population was overweight or obese adult Americans with type II diabetes.
What was the main result? The trial demonstrated that there was no reduction in the incidence of cardiovascular events in individuals with type II diabetes when lifestyle intervention was implemented.
Internal Validity
Are the results likely to be affected by observation bias? There was little opportunity for observation bias, as the measured factor was the first post-randomization incident of a composite cardiovascular event.
Are the results likely to be affected by recall bias? No, this is highly unlikely because the scientists involved in the study were measuring scientifically defined events—in this case, cardiovascular events.
Are the results likely to be affected by confounding? Because the study found no link, there is no causal relationship and the outcome is unlikely to be affected by confounding chance.
Generalizability: External validity
Can the study results be applied to the eligible population? Yes, but weight loss has been demonstrated to be helpful to other aspects of diabetes management so maintaining or gaining weight might not be recommended.
Can the study results be applied to the source population? Yes, but once again maintaining or gaining weight might have other implications.
Can the study results be applied to other relevant populations? More study would need to be done on the geriatric population, which is the only other population at risk of cardiovascular events.
Study 3 Lifestyle change and mobility in obese adults with type 2 diabetes
Description
Exposure, Intervention: Intervention was lifestyle change and intervention.
Outcome: Weight loss and fitness slowed the loss of mobility in the individuals who were chosen for the study.
Main Result
What was the exposure or intervention? The researchers designed a diabetes support and education program as well as a lifestyle intervention program.
What was the outcome? Weight loss and fitness slowed the loss of mobility in the individuals who were chosen for the study.
What was the study design? The study was a randomized trial with part of the 5145 participants assigned to each group.
What was the study population? The population was 5145 overweight or obese adults between 45 and 74 who had type II diabetes.
What was the main result? Weight loss and fitness slowed the loss of mobility in the individuals who were included in the study.
Internal Validity
Are the results likely to be affected by observation bias? It is unlikely, as the researchers measured objective variables.
Are the results likely to be affected by recall bias? It is possible, as some of the results were self-reported by the participants.
Are the results likely to be affected by confounding? It is possible that confounding would be an issue in this particular study, as there was no real control group; both groups received some sort of intervention.
Generalizability: External validity
Can the study results be applied to the eligible population? Yes, diet and exercise should be recommended to the general population with type II diabetes
Can the study results be applied to the source population? Yes, the results were generally positive for all participants.
Can the study results be applied to other relevant populations? Yes, but more research should be done into appropriate types of exercise for aging populations.
References
Diabetes Prevention Program Research Group. (2003). Reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin. The New England journal of medicine, 346(6), 393.
Look AHEAD Research Group. (2013). Cardiovascular effects of intensive lifestyle intervention in type 2 diabetes. The New England journal of medicine, 369(2), 145.
Rejeski, W. J., Ip, E. H., Bertoni, A. G., Bray, G. A., Evans, G., Gregg, E. W., & Zhang, Q. (2012). Lifestyle change and mobility in obese adults with type 2 diabetes. New England Journal of Medicine, 366(13), 1209-1217.
