Vitamin D deficiency may be tied to risk factors for type 2 diabetes among obese children researchers found.

-Team@CMHF

• Lower levels of 25-hydroxyvitamin D were associated with significantly worse results on a test of insulin resistance (HOMA-IR) and a two-hour oral glucose tolerance test (P=0.001 and P=0.04, respectively), Micah Olson, MD, of the University of Texas Southwestern Medical Center, and colleagues reported online in the Journal of Clinical Endocrinology and Metabolism.
• Low 25-hydroxyvitamin D levels may play a role in the pathophysiology of impaired glucose tolerance in obese children, they wrote.
• Studies have shown that obese pediatric patients have high rates of vitamin D deficiency, which has also been linked with cardiovascular disease and type 2 diabetes the researchers said.
• So to assess the association of low levels of 25(OH)D with insulin sensitivity, Olson and colleagues assessed 411 obese youngsters from northern Texas, ages 6 to 16, who were clients at an obesity clinic from January 2009 to March 2010.
• They also matched 89 kids who weren’t overweight to the obese group.
• They found that higher proportions of patients in the obese group had vitamin D insufficiency or deficiency than in the group that wasn’t overweight: 92% of obese patients had 25(OH)D levels below 75 nmol/L, and 50% had levels below 50 nmol/L, compared with 68% and 22%, respectively, of those who weren’t overweight.
• For this study, vitamin D insufficiency was defined as <75 140 nmol/L (30 ng/mL) and deficiency was set at <50 nmol/L (20 ng/ml).
• The group set definitions of deficiency higher than those recently recommended by the Institute of Medicine, which set deficiency at 25(OH)D levels below 30 nmol/L.
• The two strongest predictors of decreased 25(OH)D levels were skipping breakfast (P<0.001) and higher soda intake (P<0.001); lower levels were also associated with juice intake (P=0.009).
• The finding lends support to poor dietary habits playing a role in lower vitamin D levels in obese children, they wrote, adding that kids are consuming soda and juice instead of milk, which is fortified with vitamin D.
• With regard to links with risk factors for type 2 diabetes, the researchers found that, although 25(OH)D levels were negatively correlated with HOMA-IR and two-hour oral glucose tolerance testing, they weren’t associated with HbA1c or blood pressure z-scores.
• Olson and colleagues wrote that lower 25(OH)D levels in obesity may be attributable to diminished sun exposure because of a sedentary lifestyle, poor diet, and increased clearance of vitamin D due to storage in adipose tissue.
• Potential explanations for the association between low 25(OH)D levels and impaired glucose tolerance may have something to do with the direct effects of vitamin D on pancreatic beta cell insulin secretion, they wrote. Vitamin D receptors and vitamin D-binding proteins exist in pancreatic tissue, and calcium plays an essential role in beta-cell insulin secretion.
• The study was limited because physical activity and sunlight exposure couldn’t be measured in the study groups, the researchers said.
• They added that pediatricians need to be aware of the higher rates of vitamin D deficiency in obese children and the potential implications that makes for type 2 diabetes risk in this population.

For further reading log on to : http://www.medpagetoday.com/Pediatrics/Obesity/30089