Hydrochlorothiazide is a diuretic used for treating hypertension and is typically safe to use in patients with mild to moderate renal dysfunction.

Metformin is very likely to be discontinued in this patient due to her declining renal functions as indicated by decreased GFR and increased creatinine levels. Increased creatinine level can suggest that the kidney isn't processing or filtering substances as well as it should be. Metformin, which is eliminated by renal excretion, can build up in patients with renal dysfunction and may lead to lactic acidosis, a serious and potentially life-threatening condition.

Insulin does not primarily depend on the kidneys for its elimination. So, the patient's decreased renal function would not warrant discontinuation of insulin.

Glimepiride, a sulfonylurea medication, is primarily metabolized by the liver and does not warrant discontinuation due to an impaired renal function.