Age affect insulin sensitivity and the metabolism, and vitamin D status was shown to have a correlation with markers of insulin resistance. That's why, we aimed in our trial to study the effect of vitamin D supplementation on glycemic markers and index of insulin resistance.

A low serum 25-hydroxyvitamin D [(25(OH) D)] concentration was shown to correlate with higher fasting blood glucose (FBG) and insulin levels. Since age affect insulin sensitivity and the metabolism, we aimed in this randomized controlled trial to investigate the effect of vitamin D supplementation on glucose homeostasis and index of insulin resistance in elderly subjects living in Beirut, Lebanon.

Participants (n= 115) deficient in vitamin D were randomly divided into two groups, a group receiving 30,000 IU cholecalciferol/week for a period of 6 months, and a placebo group. The index of insulin resistance HOMA (homeostasis model assessment) was the primary outcome. Glucose homeostasis and metabolic markers were also measured at start of treatment and at 6 months.

Inclusion Criteria:

-Deficiency in vitamin D and having no medical history of type 2 diabetes mellitus

Exclusion Criteria:

patients with a history of type-2-diabetes, congestive heart failure, liver failure, renal failure, cancer, or taking oral hypoglycemic drugs or statin therapy, or patients having metabolic bone disease.

Neither the investigator nor the subjects were aware of the group allocation; the pharmacist (in charge of the placebo tablets as well as the packing and coding of the supplements) was the only person to know to which group each participant belonged.