2021 Clinical Practice Guidelines for Diabetes Mellitus of the Korean Diabetes Association

Abstract

The Committee of Clinical Practice Guidelines of the Korean Diabetes Association (KDA) updated the previous clinical practice guidelines for Korean adults with diabetes and prediabetes and published the seventh edition in May 2021. We performed a comprehensive systematic review of recent clinical trials and evidence that could be applicable in real-world practice and suitable for the Korean population. The guideline is provided for all healthcare providers including physicians, diabetes experts, and certified diabetes educators across the country who manage patients with diabetes or the individuals at the risk of developing diabetes mellitus. The recommendations for screening diabetes and glucose-lowering agents have been revised and updated. New sections for continuous glucose monitoring, insulin pump use, and non-alcoholic fatty liver disease in patients with diabetes mellitus have been added. The KDA recommends active vaccination for coronavirus disease 2019 in patients with diabetes during the pandemic. An abridgement that contains practical information for patient education and systematic management in the clinic was published separately.

Keywords: Diabetes mellitus; Diagnosis; Practice guideline; Therapeutics.

Fig. 1.

Treatment algorithm 1 (initial therapy) for patients with type 2 diabetes mellitus (T2DM). The algorithm stratifies the strategy of glycemic control for T2DM based on initial glycosylated hemoglobin (A1C) levels and underlying comorbidities. For newly diagnosed T2DM, begin with comprehensive lifestyle modification (LSM) at the time of diagnosis and monitor continuously. If the initial severe hyperglycemia (A1C level >9.0%) is accompanied by symptoms of hyperglycemia (polydipsia, polyuria, weight loss, etc.), insulin treatment should be prioritized (algorithm 3). If heart failure (HF), established atherosclerotic cardiovascular disease (eASCVD), or chronic kidney disease (CKD) are present, follow algorithm 4. If glycemic target is not achieved within 3 months after LSM, then glucose-lowering agent should be initiated promptly. If the current A1C is 1.5% higher than that of the target A1C or the current A1C level is >7.5%, follow algorithm 2 (combination therapy). If the A1C level is 7.5% or less, metformin monotherapy is recommended as a first-line therapy. However, if there are contraindications or intolerable side effects related to metformin use, a different class of medications can be considered. Instead of metformin monotherapy, early combination therapy could be considered to reduce the risk of failure of glycemic control in some patients with newly diagnosed T2DM. eGFR, estimated glomerular filtration rate. ^aParticularly HF with reduced ejection fraction (HFrEF, clinical diagnosis of HF and left ventricular ejection fraction ≤40%), ^bA history of an acute coronary syndrome or myocardial infarction, stable or unstable angina, coronary heart disease with or without revascularization, other arterial revascularization, stroke, or peripheral artery disease assumed to be atherosclerotic in origin, ^ceGFR <60 mL/min/1.73 m² or urine albumin creatinine ratio ≥30 mg/g.

Fig. 2.

Treatment algorithm 2 (combination therapy) for patients with type 2 diabetes mellitus (T2DM). If the current glycosylated hemoglobin (A1C) is 1.5% higher than that of the target A1C or the current A1C level is >7.5%, combination therapy is recommended. If the target A1C level has not been achieved, the up-titration of existing medication, combination therapy using medications with different mechanisms of action, or use of injectable medication should actively be considered as soon as possible. When choosing glucose-lowering agents, consider glucose-lowering efficacy, hypoglycemia risk or weight change, side effects, treatment acceptability, age, personal value of life, and cost. The characteristics of glucose-lowering agents are expressed as a bar scale. Each color shows glycemic efficacy (green), hypoglycemia risk (red), and body weight change (yellow). HF, heart failure; eASCVD, established atherosclerotic cardiovascular disease; CKD, chronic kidney disease; eGFR, estimated glomerular filtration rate; DPP-4i, dipeptidyl peptidase-4 inhibitor; TZD, thiazolidinedione; SU, sulfonylurea; GLP-1RA, glucagon-like peptide-1 receptor agonist; SGLT2i, sodium-glucose cotransporter 2 inhibitor; α-GI, alpha-glucosidase inhibitor. ^aParticularly HF with reduced ejection fraction (HFrEF, clinical diagnosis of HF and left ventricular ejection fraction ≤40%), ^bHistory of acute coronary syndrome or myocardial infarction, stable or unstable angina, coronary heart disease with or without revascularization, other arterial revascularization, stroke, or peripheral artery disease assumed to be atherosclerotic in origin, ^ceGFR <60 mL/ min/1.73 m² or urine albumin creatinine ratio ≥30 mg/g, ^dGlinide can be used as a dual therapy with metformin, TZD, α-GI, or insulin. Glinide can be used as a triple therapy with metformin and α-GI, metformin and TZD, or metformin and insulin.

Fig. 3.

Treatment algorithm 3 (injectable therapy) for patients with type 2 diabetes mellitus (T2DM). If the glycosylated hemoglobin (A1C) level is >9.0% and symptomatic hyperglycemia or metabolic decompensation is present, insulin therapy can be initiated with or without oral anti-diabetic drug (OAD) in patients with T2DM. Injectable therapy (glucagon-like peptide-1 receptor agonist [GLP-1RA] or insulin) is recommended when potent glucose-lowering efficacy is required. The addition of GLP-1RA, basal insulin, or premixed insulin is recommended equally. If A1C target is not achieved with GLP-1RA or basal insulin-based therapy, free or fixed-ratio combination therapy of GLP-1RA and basal insulin could be considered. Intensification of insulin therapy with premixed insulin twice daily, basal-plus, or basal-bolus is also recommended to enhance blood glucose control.

Fig. 4.

Treatment algorithm 4 (comorbidities) for patients with type 2 diabetes mellitus who have heart failure (HF), established atherosclerotic cardiovascular disease (eASCVD), or chronic kidney disease (CKD). If patients have underlying above comorbidities, glucose-lowering agents, including sodium-glucose cotransporter 2 (SGLT2) inhibitor or glucagon-like peptide-1 receptor agonist (GLP1-RA), are the preferred choice. For patients with HF, glucose-lowering agents, including SGLT2 inhibitors with proven cardiovascular (CV) benefits, should be prioritized. Regimens that include SGLT2 inhibitors or GLP-1RAs with proven CV benefits should be prioritized for combination therapy in patients with eASCVD. For patients with albuminuria or reduced estimated glomerular filtration rate (eGFR), glucose-lowering agents, including SGLT2 inhibitors with proven renal and CV benefits, should be prioritized. A1C, glycosylated hemoglobin; Met, metformin; TZD, thiazolidinedione. ^aParticularly HF with reduced ejection fraction (HFrEF, clinical diagnosis of HF and left ventricular ejection fraction ≤40%), ^bHistory of acute coronary syndrome or myocardial infarction, stable or unstable angina, coronary heart disease with or without revascularization, other arterial revascularization, stroke, or peripheral artery disease assumed to be atherosclerotic in origin, ^ceGFR <60 mL/min/1.73 m² or urine albumin creatinine ratio ≥30 mg/g, ^dDapagliflozin, empagliflozin, ertugliflozin, ^eDapagliflozin, empagliflozin, ^fDulaglutide, liraglutide, semaglutide, ^gPioglitazone.