Depression Linked to Low Insulin Sensitivity in Type 2 Diabetes

Results of a study of depressed adults in a diabetes prevention program at the University of Connecticut were announced at the American Diabetes Association (ADA) 69th Scientific Sessions.

Julie Wagner, PhD, associate professor in the Division of Behavioral Sciences and Community Health at the University of Connecticut Health Center, presented findings from 56 obese adults at risk for Type 2 diabetes and symptoms of metabolic syndrome.

Mean age was 46 years (±13 years), mean body mass index was 39 kg/m2 (±7 kg/m2), mean waist circumference was 44 inches (±7 inches), mean fasting glucose was 96 mg/dL (±12 mg/dL), and whole-body insulin sensitivity was 3.1 (±1.9). Of the cohort, 90% were female and 53% were white.

Other risk factors for Type 2 diabetes included family history, gestational diabetes, delivery of a baby of 9 pounds or larger, hypertension, high low-density-lipoprotein cholesterol, high triglycerides, and low high-density-lipoprotein cholesterol.

Individuals with a history of a 2-hour postprandial glucose load of 200 mg/dL or higher or a history of treatment with metformin for impaired glucose tolerance were excluded from the study.

Subjects were categorized into 1 of 3 groups: nondepressed (57%); depressed (23%), defined as a score of 16 or greater on the Centers for Epidemiologic Studies Depression (CESD) Scale; or treated for depression (20%).

Mean CESD score was 5.2 (±3.0) for nondepressed subjects; 28.6 (±9.6) for depressed subjects; and 19.6 (±12.2) for those treated for depression.

Dr. Wagner noted that approximately half of those treated for depression (46%) scored above 16 on the CESD Scale. That is, these patients still showed signs of significant depression despite treatment.

Level of physical activity was documented using the Physical Activity subscale of the Health Promoting Lifestyle Profile 4-point scale. Dr. Wagner reported that depression scores were inversely correlated with physical activity (r = –0.36) and insulin sensitivity (r = –0.30).

Subjects with untreated depression had significantly lower insulin sensitivity (mean insulin sensitivity, 1.79 ± 0.91) than nondepressed individuals (mean insulin sensitivity, 3.39 ± 1.78; P < .05).

Adults treated for depression had insulin sensitivities similar to nondepressed adults (mean, 3.10 ± 1.86; P = .63). The association remained after controlling for physical activity (P = .28).

"Depressed subjects have a 37% increased risk of developing diabetes," Dr. Wagner noted during her presentation. "Evidence indicates that insulin resistance and depression are related."

Dr. Wagner stated that, "Treatment for depression in adults at risk for Type 2 diabetes may improve insulin resistance…. Further research is needed to determine if treatment of depression contributes to delaying or decreasing the risk for Type 2 diabetes."

Dr. Robertson mentioned that, "Depression is tied up with a lot of the issues surrounding diabetes. Obesity is a big part of this disease, and the more overweight patients are, the more depressed they get, and the more inactive they get, as you can see in [Dr. Wagner's] study, the worse the depression. It is a vicious cycle."

"Effective treatment of the depression might [stop] the cycle," Dr. Robertson said. "With effective treatment, patients will tend to change some of their other behaviors" that increase the risk for Type 2 diabetes.

"The bigger question," Dr. Robertson observed, "is whether the depression is part of the diabetes or part of chronic disease in general."

American Diabetes Association (ADA) 69th Scientific Sessions: Abstract 1850-P. Presented June 8, 2009.