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BMI is strongly and independently associated with T2DM
Not only is BMI strongly and independently associated with the risk of being diagnosed with type 2 diabetes, but BMI categories were increasingly more likely to be diagnosed with T2DM than individuals in lower BMI categories, according to a study published online in Diabetology & Metabolic Syndrome.
Researchers from Evidera and Novo Nordisk conducted a case–control study to assess the association between BMI and the risk of being diagnosed with T2DM in the US. Using an electronic health records database (Geisinger Health System), they selected adults who were diagnosed with T2DM (defined by ICD-9-CM diagnosis codes or use of anti-diabetic medications) between January 2004 and October 2011.
Twice as many individuals enrolled in the health system without a T2D diagnosis during the study period (controls) were selected based on age, sex, history of cardiac comorbidities or hyperinflammatory state (defined by C-reactive protein and erythrocyte sedimentation rate), and use of psychiatric or beta blocker medications.
BMI was measured during one year prior to the first observed T2DM diagnosis (for cases) or a randomly assigned date (for controls); individuals with no BMI measure or BMI < 18.5 kg/m2 were excluded. They then assessed the impact of increased BMI on a T2DM diagnosis using odds ratios (OR) and relative risks (RR) estimated from multiple logistic regression results.
The study included 12,179 T2DM cases (mean age: 55, 43% male) and 25,177 controls (mean age: 56, 45% male). Compared with control individuals, the case individuals had higher baseline BMI values (mean ± standard deviation: 35.4 ± 8.5 kg/m2 vs. 29.4 ± 6.3 kg/m2, p<0.01). Cases were more likely to be younger, male, and to have higher healthcare resource use as measured by costs during the 12-month pre-index period than controls.
Cases were also more likely to have experienced comorbidities related to diabetes and/or obesity and used medications related to diabetes or obesity during the 12-month pre-index period than controls.
They also found that the change in the magnitude of the ORs from one BMI category to the next was larger for individuals in higher BMI categories than individuals in lower BMI categories. The patterns of ORs and relative risks imply that individuals in higher BMI categories were increasingly more likely to be diagnosed with T2DM than individuals in lower BMI categories (p< 0.05).
Other individual characteristics, aside from BMI, were also significantly associated with the risk of being diagnosed with T2D including :
- Age, 45–64 years old compared with 18–44 years old
- Ethnicity, black or other race compared with white
- Smokers (compared with never) were associated with an increased risk of T2DM
In addition, individuals who experienced comorbidities (any cardiac comorbidities, hyperinflammatory state, or depression) or who used medications (psychiatric drugs, antidepressants or anxiolytics, antihyperlipidemia drugs, and antihypertensives) were more likely to have been diagnosed with T2D than those who did not.
“The risk of developing T2DM for individuals who were overweight or obese was about 1.5–5 times higher than for individuals with normal BMI, as estimated in our study,” the authors write. “This demonstrates the importance of continuous weight management, which not only can reduce the disease burden of obesity but also may prevent further progression to T2DM. Further research on the association between BMI and the risk of developing T2D should include the time to the incident T2D diagnosis and, if data are available, account for individuals’ pre-diabetic status and the timing and duration of obesity.”
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