Depression linked to diabetes: What is the missing link?
A new study in the November 22 issue of Archives of Internal Medicine suggests people with diabetes may be at a higher risk for depression and those with depression may be at higher risk for type 2 diabetes mellitus.
An Pan, Ph.D., of the Harvard School of Public Health, Boston, and colleagues found women with depression were 17 percent more likely to develop type 2 diabetes mellitus after adjustment for other confounders such as physical activity and body mass index.
They also found women taking antidepressants were 25 more likely to develop diabetes than those who did not have depression.
Additionally, women with type 2 diabetes mellitus were at 29 percent increases risk of depression. And taking insulin for diabetes was linked with 53 percent increased risk of depression.
It is unknown whether using antidepressant boosted the risk of diabetes and using insulin increased risk of depression.
About 23.5 million U.S. adults live with diabetes and 14.8 million suffer depression each year, according to the press release posted by the journal.
For the study, Pan et al. classified women who reported symptoms of depression, used antidepressant medications or were diagnosed with depression by a physician as having depression.
The researchers followed 55,000 U.S. women for 10 years during which 2,844 women were diagnosed with type 2 diabetes mellitus and 7,415 experienced depression.
Depression was associated with type 2 diabetes mellitus. Using antidepressants was linked with higher risk of diabetes and using insulin was correlated with higher risk of depression.
"Depression and diabetes are closely related to each other, and this reciprocal association also depends on the severity or treatment of each condition," the authors wrote. "All the associations were independent of sociodemographic, diet and lifestyle factors."
The researchers said the associations were affected by lifestyle factors such as physical activity and BMI, but they also said these factors are not the only things that have an impact on the association.
One factor Pan et al. did not mention that may serve as the link between depression and diabetes mellitus is vitamin D insufficiency.
Boucher B.J. of Queen Mary University of London reported on Aug 27 2010 in Current Drug Targets that hypovitaminosis D may be the cause for a number of health conditions including type 2 diabetes mellitus as vitamin D insufficiency was found to increase insulin resistance, reduce insulin secretion and increase autoimmune or inflammatory damage to pancreatic islets.
On the other hand, quite some studies have associated low vitamin D levels with high risk of depression.
Ganji V. and colleagues published a study in the Nov 11, 2010 issue of International Archives of Medicine showing that the likelihood of having depression in people with vitamin D deficiency is significantly higher, compared with those with vitamin D sufficiency.
Lee D.M. and colleagues from the University of Manchester in the U.K. also reported in the Sep 7, 2010 issue of Journal of Psychopharmacology that vitamin D levels were inversely associated with depression risk.
Evidence suggests that type 2 diabetes mellitus and depression may share some same risk factors and vitamin D could be one of them.
Editor' note: Enjoy the article as no other media report gives out the evidence suggesting that depression was associated with type 2 diabetes through a common risk factor - vitamin D insufficiency.
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