WEDNESDAY, Dec. 2 (HealthDay News) -- Adolescents with type 1 diabetes (T1D) but normal weight, body composition, and serum lipid profile may still have insulin resistance (IR) and impaired cardiovascular function, traits usually associated with type 2 diabetes and obesity, according to a study published online Nov. 13 in the Journal of Clinical Endocrinology & Metabolism.

Kristen J. Nadeau, M.D., of the University of Colorado Denver, and colleagues studied 12 adolescents (ages 12 to 19) with T1D, and compared them with a control group of 12 nondiabetic adolescents of similar age, stage of puberty, activity level, and body mass index (BMI). The researchers evaluated the subjects' peak oxygen consumption (VO₂peak), IR, cardiac function, vascular function, intramyocellular lipids (IMCL), body composition, and other characteristics.

The T1D adolescents were found to have significantly reduced VO₂peak, peak work rate and insulin sensitivity compared to the nondiabetic adolescents, as well as reduced vascular reactivity and evidence of left ventricular hypertrophy and diastolic dysfunction. Surprisingly, the IR was manifested in a phenotype characterized by normal IMCL, body composition, waist-to-hip ratio, serum lipids, triglyceride-to-high-density lipoprotein ratio, and BMI.

"In addition, our data present a paradigm shift away from the traditional model of IR as being synonymous with the metabolic syndrome phenotype. We instead observed IR in T1D subjects without typical features of the metabolic syndrome, creating an entirely unique phenotype. Our data also suggest that IR may be a common, integral component of T1D pathophysiology. Elucidating the mechanisms underlying IR in adolescents with T1D will direct future research and therapeutic interventions," the authors write.

Several study authors reported receiving research support from the National Institutes of Health, the Department of Veterans Affairs, and other non-commercial sources.

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