Type 2 diabetes mellitus (T2DM) is a major public health problem .Prevalence of vitamin D deficiency is also high i.e. 78-96% in different groups of population in north India. Observational studies find association between low Vitamin D status and type 2 diabetes mellitus. Prediabetes is a condition that progress to diabetes at a rate of 6-10% per year .There is mechanistic support that vitamin D may influence both insulin secretion and insulin sensitivity and subsequently T2DM incidence. In general, cross-sectional and prospective studies support the role of vitamin D in the prevention of T2DM. This study will be a single blind randomized placebo controlled trial to study the effect of oral cholecalciferol in insulin sensitivity and secretion in adults with prediabetes who are also vitamin D insufficient.

Inclusion Criteria:

• Adults > 20 years
• Impaired fasting glucose (IFG) - FPG 100-125 mg/dl
• Impaired glucose tolerance((IGT)- 2hr PPG 140-199mg/dl

OR

• both ( IFG +IGT)
• with or without Hb A1c -5.7-6.4 %

WITH

• Asymptomatic Vitamin D deficiency(< 20ng/ml) or vitamin D in sufficiency(< 32ng/ml)

Exclusion Criteria:

• Diabetes mellitus,
• Base line 25(OH)D3 > 32 ng/ml,
• Symptomatic vitamin D deficiency,
• Any medication within last month that could affect insulin secretion, insulin sensitivity , vitamin D and calcium metabolism
• Chronic renal , hepatic ,malignant, intestinal or endocrine diseases
• Febrile illness or infective morbidity in last 2 weeks,
• Grossly deranged liver and kidney function