Having excess visceral fat and insulin resistance — but not being obese in and of itself — appears to put heavier patients at risk for prediabetes and diabetes….
According to James de Lemos, MD, of the University of Texas Southwestern Medical Center in Dallas, Texas, and colleagues, among obese adults, visceral fat was associated with more than a twofold increased risk of developing incident diabetes (odds ratio 2.42, 95% CI 1.59 to 3.68).
In addition, developing either condition was also associated with markers of insulin resistance including elevated fructosamine levels (OR 1.95, 95% CI 1.43 to 2.67) and elevated fasting blood glucose (OR 1.88, 95% CI 1.38 to 2.56).
But there were no associations with general markers of obesity, including body mass index (BMI) or total body fat.
The researchers wrote, "Our study may have implications for understanding differences between metabolically healthy and pathologic obesity."
The risk of developing type 2 diabetes is diverse among obese patients, and factors that discriminate risk of developing the condition haven’t been well studied.
So the researchers looked at associations between prediabetes and diabetes and baseline adipose tissue distribution, adipokines, lipids, biomarkers of insulin resistance, as well as family history of diabetes and factors at follow-up in "a multiethnic cohort of obese adults [≤30 kg/m2] with extensive cardiovascular, metabolic, and adipose tissue phenotyping" enrolled in the Dallas Heart Study from 2000 to 2002.
A total of 732 participants received multiple surveys, laboratory testing, and imaging studies. Fasting blood glucose was sampled in a subgroup of 512 participants at baseline.
Data was collected on body surface area, waist circumference, lower body fat, visceral and subcutaneous abdominal fat, liver fat, as well as levels of leptin, adiponectin, high-sensitivity C-reactive protein, fructosamine, low-density lipoprotein, high density lipoprotein, and very low density lipoprotein. The researchers used electron-beam CT to measure coronary artery calcium.
In participants without diabetes at baseline, a number of factors were significantly and independently associated with incident diabetes in obese adults:
- Elevated visceral fat: OR 2.42, 95% CI 1.59 to 3.68 (P<0.001)
- Elevated systolic blood pressure: OR 1.26, 95% CI 1.07 to 1.48 (P=0.006)
- Elevated fructosamine levels: OR 1.95, 95% CI 1.43 to 2.67 (P<0.001)
- Elevated fasting blood glucose: OR 1.88, 95% CI 1.38 to 2.56 (P<0.001)
- Weight gain from baseline: OR 1.06, 95% CI 1.02 to 1.10 (P=0.002)
- Family history of diabetes: OR 2.32, 95% CI 1.25 to 4.29 (P=0.008)
There were no associations for BMI, total body fat, or abdominal subcutaneous fat, they reported. Additionally, among participants with normal fasting blood glucose at baseline, factors significantly associated with incident prediabetes and diabetes were:
- Higher visceral fat mass: OR 1.48, 95% CI 1.17 to 1.88 (P=0.001)
- Elevated fructosamine levels: OR 1.42, 95% CI 1.14 to 1.75 (P=0.001)
- Elevated insulin level: OR 1.34, 95% CI 1.06 to 1.70 (P=0.01)
- Older age, per 10 years: OR 1.48, 95% CI 1.17 to 1.86 (P=0.001)
- Non-white race: OR 1.77, 95% CI 1.08 to 2.91 (P=0.02)
- Family history of diabetes: OR 1.60, 95% CI 1.05 to 2.44 (P=0.03)
- Weight gain from baseline: OR 1.08, 95% CI 1.05 to 1.10 (P<0.001)
Again, there was no association with measures of general adiposity, they reported.
The authors concluded that "a dysfunctional adiposity phenotype, characterized by excess visceral fat and biomarkers of insulin resistance," was independently associated with development of prediabetes and diabetes, and said their findings suggest that "clinically measurable markers of adipose tissue distribution and insulin resistance may be useful in prediabetes and diabetes risk discrimination among obese individuals."
The researchers noted that the number of diabetes events were modest, and time to diabetes or prediabetes onset was not measured. They also said the study was limited by a lack of generalizability and missing glucose tolerance testing and measures of average blood glucose in the Dallas cohort.
- There were no associations between prediabetes or diabetes incidence with general markers of obesity, such as body mass index (BMI) or total body fat
- Having excess visceral fat and insulin resistance, but not being obese in and of itself, puts heavier patients at risk for prediabetes and diabetes, researchers found.
de Lemos JA, et al "Dysfunctional adiposity and the risk of prediabetes and type 2 diabetes in obese adults" JAMA 2012; 308:1150-1159.