Assertion: Diabetes mellitus is caused due to lack of insulin in the body.
Reason: Insulin helps in utilisation of glucose in the body.
(1)
Insulin is a hormone released by the beta cells of the pancreas. It maintains the blood glucose level in the body, by its proper utilisation. So, lack of insulin causes accumulation of glucose in the blood and hence a disease called diabetes mellitus is caused. Thus, both assertion and reason are correct and reason is the correct explanation of the assertion.