Brand name: Glumetza. Initially, it is administered at 500mg daily with meals and later adjusted to 1000mg, 500mg XR, or 1000mg XR. It acts by suppressing gluconeogenesis in the liver and reducing glucose absorption in the small intestines, reducing insulin resistance. Common side effects: bloating, lactic acidosis, nausea, gastrointestinal upset, loss of weight, and deficiency of vitamin B12. Furthermore, the initiation of metformin is associated with the development of hemolytic anemia (Miller & Fortun, 2018). It should be cautiously administered in pregnant and alcoholic patients. In conditions such as renal insufficiency, there is reduced medication clearance, thus leading to toxicity.
To reduce side effects related to the gastrointestinal system during the first treatment, metformin should be taken with meals. Once treatment has been initiated with metformin, it should not be discontinued unless the patient develops contraindication (Miller & Fortun, 2018). For individuals with renal failure, myocardial infarction, diabetic ketoacidosis, and heart failure, metformin should not be initiated or stopped if the patient develops these conditions while undergoing treatment.
Metformin should not be administered to patients with glomerular filtration rates (GFR) of thirty or below. Patients with a glomerular filtration rate of forty-five or more can safely use metformin (Miller & Fortun, 2018). Therefore, patients with GFR lower than forty-five on this medication should be closely monitored. Additionally, the patients’ prescriber should assess the risk and the merits of the continued drug therapy for patients with GFR lower than forty-five. It is essential to monitor the kidney function of the patients. It is considered first-line therapy in addition to lifestyle modification. Upon initiation of insulin therapy, metformin should also be started for metabolic benefits.
Classified into:
  * Basal: agents in this group are neutral protamine Hagedorn (NPH) with an onset of 2-4 hours and act for ten to about sixteen hours. It reaches its peak at 4-10 hours. It causes an increased risk of nocturnal hypoglycemia (Gupta, 2022). Another group is glargine, detemir, and degludec, which have an onset of one to four and act up to twenty-four hours. They have a reduced risk of nocturnal hypoglycemia as compared to NPH. Basal insulin acts by suppressing the production of glucose in the liver. Basal prandial: includes Regular U 500. Its onset is at half an hour, reaching its peak after two to three hours. It should be administered half an hour before meals (Gupta, 2022). These agents provide a long duration of action. Basal prandial is highly recommended for individuals who have high insulin resistance.
  * Prandial: includes regular human insulin, which acts up to 8 hours and starts its action after one hour. It should be given thirty minutes before meals because otherwise, there is an increased risk of hypoglycemia. Another agent is aspart, glulisine, and lispro. Prandial insulins act rapidly. They have a reduced risk of postprandial hypoglycemia as compared to regular insulin. Human insulin can either be short-acting, intermediate-acting, or pre-mixed. Short-acting insulin includes human R and Novolin R (Gupta, 2022). They have an onset of thirty to one hour and reach their peak at two to four hours. The intermediate-acting acts for 12-16 hours and begins from one to three hours. Examples are Humulin N and Novolin N. The pre-mixed insulin has a varying peak but begins acting from 30 minutes to one hour.