The answer is the first one (a): Lifestyle changes.
Explanation for each option:
a. Lifestyle changes - This is the correct answer. The first-line treatment for Type 2 Diabetes Mellitus (T2DM) typically involves lifestyle modifications, including diet and exercise, to help manage blood glucose levels and improve overall health.
b. Oral hypoglycemic medications - While these are commonly used in the management of T2DM, they are usually considered after lifestyle changes have been implemented and if additional glycemic control is needed.
c. Insulin - Insulin is generally not the first-line treatment for T2DM. It is typically reserved for cases where blood glucose levels cannot be adequately controlled with lifestyle changes and oral medications.
d. All of the above - This option is incorrect because insulin is not part of the first-line treatment for T2DM.
In summary, the first-line treatment for T2DM is lifestyle changes, focusing on diet and exercise to manage the condition effectively.