Diabetes mellitus is caused due to the deficiency of:

$A$ sample of urine was diagnosed to contain a high content of glucose and ketone bodies. Based on this observation, answer the following:
$(a)$ Which endocrine gland and hormone is related to this condition?
$(b)$ Name the cells on which this hormone acts.
$(c)$ What is the condition called and how can it be rectified?

Give a reason: Pancreas is an endocrine as well as an exocrine gland.

Insulin was isolated from the pancreas of a dog by:

The element present in traces in insulin is:

Name a peptide hormone which acts mainly on hepatocytes, adipocytes and enhances cellular glucose uptake and utilisation.