The purpose of the study is to assess the relationship between vitamin D status and insulin- glucose dynamics in obese Adolescents. The study is intended to assess the difference in the insulin sensitivity before and after correction of vitamin D deficiency.

The vitamin D deficient subjects are identified initially through an existing study. Those identified with vitamin D deficiency are notified and subsequently treated with standard therapy for vitamin D deficiency as part of their clinical care. Patients who self report that they have taken the treatment are enrolled in this study. Patients will be evaluated in this study with measurement of serum 25 OH D level, PTH and oral glucose tolerance test. The study will assess if there is improvement in glucose- insulin sensitivity dynamics once the serum 25OH D level is normalized

Inclusion Criteria:

• Female adolescents who are menarchal
• BMI is 95th centile, for age and sex
• Patients will be screened for vitamin D deficiency through an existing study.
• Those found to be vitamin D deficient will be given standard treatment of vitamin D deficiency.
• In this study, patients who self report that they had taken the treatment for vitamin D will be screened for serum 25 OH D level

Exclusion Criteria:

• Children with diabetes, other endocrine or acute or chronic medical illnesses, children on oral contraceptive pills, diuretics and anticonvulsant medications

Female adolescents who are menarchal BMI is 95th centile, for age and sex