Executive Summary and Recommendations A diagnosis of diabetes or hyperglycemia should be confirmed prior to ordering, dispensing, or administering insulin (A).Insulin is the primary treatment in all patients with type 1 diabetes mellitus (T1DM) (A).Typically, patients with T1DM will require initiation with multiple daily injections at the time of diagnosis. This is usually short-acting insulin or rapid-acting insulin analogue given 0 to 15 min before meals together with one or more daily separate injections of intermediate or long-acting insulin. Two or three premixed insulin injections per day may be used (A).The target glycated hemoglobin A1c (HbA1c) for all children with T1DM, including preschool children, is recommended to be < 7.5% (< 58 mmol/mol). The target is chosen aiming at minimizing hyperglycemia, severe hypoglycemia, hypoglycemic unawareness, and reducing the likelihood of development of long-term complications (B).For patients prone to glycemic variability, glycemic control is best evaluated by a combination of results with self-monitoring of blood glucose (SMBG) (B).Indications for exogenous insulin therapy in patients with type 2 diabetes mellitus (T2DM) include acute illness or surgery, pregnancy, glucose toxicity, contraindications to or failure to achieve goals with oral antidiabetic medications, and a need for flexible therapy (B).In T2DM patients, with regards to achieving glycemic goals, insulin is considered alone or in combination with oral agents when HbA1c is ≥ 7.5% (≥ 58 mmol/mol); and is essential for treatment in those with HbA1c ≥ 10% (≥ 86 mmol/mol), when diet, physical activity, and other antihyperglycemic agents have been optimally used (B).The preferred method of insulin initiation in T2DM is to begin by adding a long-acting (basal) insulin or once-daily premixed/co-formulation insulin or twice-daily premixed insulin, alone or in combination with glucagon-like peptide-1 receptor agonist (GLP-1 RA) or in combination with other oral antidiabetic drugs (OADs) (B).If the desired glucose targets are not met, rapid-acting or short-acting (bolus or prandial) insulin can be added at mealtime to control the expected postprandial raise in glucose. An insulin regimen should be adopted and individualized but should, to the extent possible, closely resemble a natural physiologic state and avoid, to the extent possible, wide fluctuating glucose levels (C).Blood glucose monitoring is an integral part of effective insulin therapy and should not be omitted in the patient’s care plan. Fasting plasma glucose (FPG) values should be used to titrate basal insulin, whereas both FPG and postprandial glucose (PPG) values should be used to titrate mealtime insulin (B).Metformin combined with insulin is associated with decreased weight gain, lower insulin dose, and less hypoglycemia when compared with insulin alone (C).Oral medications should not be abruptly discontinued when starting insulin therapy because of the risk of rebound hyperglycemia (D).Analogue insulin is as effective as human insulin but is a...