Abstract: The worldwide prevalence of diabetes has risen dramatically over the past two decades from an estimated 30 million cases in 1985 to 382 million in 2013. The traditional anti diabetic drugs have several drawbacks in long term use. Thiamine is a member of the vitamin B family. Thiamine is necessary for normal insulin synthesis and secretion. So it may be beneficial in diabetic persons where insulin synthesis and secretion are disturbed. Albino rats used in this study was divided into four groups; six rats in each group. The groups were normal control, diabetic control, non-diabetic rats treated with thiamine and diabetic rats treated with thiamine. Diabetes was produced by intraperitoneal injection of Streptozotocin in the dose of 60 mg/kg. Fifteen minutes before streptozotocin administration nicotinamide was administered 120 mg/ kg intraperitoneally. Thiamine was given to the respective group for a period of 6 weeks. Fasting blood glucose was estimated at the end of every week. In non-diabetic rats thiamine showed no significant effect in lowering fasting blood sugar level. In diabetic albino rats thiamine normalized fasting blood glucose in six weeks. Thiamine does not affect the fasting blood glucose level of the normal rat but this effect was found significant in streptozotocin induced diabetic albino rats in six weeks period.