Diabetes mellitus (Type 2): clinical approach
文摘
科学
2024-07-08 07:00
澳大利亚
If you would like to view past exciting content, please click on the following link.Diabetes mellitus is a condition characterized by the inability to properly transport glucose from the bloodstream into cells. There are two main types of diabetes mellitus: type 1 and type 2. The primary distinction between these types lies in their underlying mechanisms. Type 2 diabetes mellitus typically occurs in individuals with obesity and is marked by insulin resistance, where peripheral tissues become less responsive to insulin.Due to this resistance, the beta cells in the pancreas increase their production of insulin to facilitate glucose movement from the blood into tissue cells. However, over time, these beta cells may become impaired and fail to produce adequate insulin, leading to reduced insulin secretion and elevated blood glucose levels. This progression can lead to various clinical states, from prediabetes and diabetes mellitus to severe, life-threatening conditions such as hyperosmolar hyperglycemic state (HHS) and diabetic ketoacidosis (DKA).In cases where type 2 diabetes mellitus is suspected, an initial ABCDE assessment should be conducted to determine the patient's stability. If unstable, immediate measures should include stabilizing the airway, breathing, and circulation, potentially requiring intubation. Establishing IV access and initiating IV fluids for volume resuscitation are crucial, along with continuous monitoring of vital signs like pulse oximetry, blood pressure, and heart rate.For unstable patients with suspected HHS or DKA, a focused history and physical exam should be obtained, along with necessary laboratory tests such as random blood glucose, serum osmolality, basic metabolic panel (BMP), urinalysis, hemoglobin A1c, and arterial blood gas (ABG) or venous blood gas (VBG). It’s essential to gather a thorough history from charts and discussions with caretakers, especially if the patient is too disoriented to provide information. Symptoms may include fatigue, headaches, excessive thirst (polydipsia), and excessive urination (polyuria), often with recent fever or infection, or disruption to their diabetes management.In HHS, labs typically show extremely high random blood glucose levels, often above 600 mg/dL, and elevated serum osmolality, usually over 320 mOsm/L. BMP may indicate electrolyte imbalances like hyponatremia and hypokalemia, along with increased BUN and creatinine. In contrast, DKA usually presents with high blood glucose levels above 250 mg/dL but lower than in HHS, with normal serum osmolality, mild ketonuria, and an elevated anion gap metabolic acidosis.Once these signs are confirmed, a diagnosis of HHS or DKA can be made. Treatment involves IV fluid resuscitation to address dehydration and hyperosmolality, electrolyte replacement, and possibly an IV insulin drip. Addressing any underlying or precipitating factors is also crucial.For stable patients, the assessment focuses on gathering a detailed history and physical examination. Symptoms might include unintentional weight loss, increased thirst and urination, and blurred vision. Risk factors often reported include a sedentary lifestyle, age over 45, a family history of type 2 diabetes, or gestational diabetes history.Occasionally, the sole symptom a patient might exhibit is numbness or tingling in the extremities, suggesting peripheral neuropathy. Upon examination, common findings include obesity, acanthosis nigricans, and reduced sensitivity to pinprick in the distal extremities. Additionally, diminished sensation might be noted during monofilament testing on the sole. In such cases, type 2 diabetes mellitus should be suspected, prompting further investigation through laboratory tests such as hemoglobin A1c, random blood glucose, fasting blood glucose, and possibly an oral glucose tolerance test (OGTT).To interpret lab results for a diagnosis, consider the following: If hemoglobin A1c is below 5.7%, fasting blood glucose is under 100 mg/dL, random blood glucose is less than 200 mg/dL, and the 2-hour OGTT glucose is below 140 mg/dL, alternative diagnoses should be explored.Conversely, a hemoglobin A1c ranging from 5.7% to 6.5%, fasting blood glucose between 100 and 126 mg/dL, random blood glucose below 200 mg/dL, or a 2-hour OGTT glucose between 140 and 199 mg/dL suggests prediabetes. For these patients, lifestyle changes such as a healthier diet and increased physical activity are recommended to reduce the risk of progressing to type 2 diabetes mellitus. In high-risk cases, an oral hypoglycemic like metformin might be prescribed, with annual diabetic screening tests advised.A diagnosis of diabetes mellitus is confirmed with a hemoglobin A1c of 6.5% or higher, fasting blood glucose of 126 mg/dL or more, random blood glucose of at least 200 mg/dL, or a 2-hour OGTT glucose of 200 mg/dL or more. Further testing should include glutamic acid decarboxylase (GAD65) antibodies, islet cell (ICA2) antibodies, and C-peptide levels to determine the specific type of diabetes.If GAD65 or ICA antibodies are positive and C-peptide levels are low, type 1 diabetes mellitus is indicated. Conversely, if GAD65 and ICA2 antibodies are negative and C-peptide levels are normal, it indicates type 2 diabetes mellitus.Upon diagnosing type 2 diabetes mellitus with a hemoglobin A1c between 6.5% and 10%, initiate metformin and advise dietary and lifestyle modifications. Schedule quarterly follow-ups to monitor hemoglobin A1c and annual examinations for diabetic retinopathy and neuropathy, including retinal and foot exams, as well as nephropathy screening through serum eGFR and urine microalbumin tests.Three months post-treatment, reassess hemoglobin A1c to determine the adequacy of the response. If hemoglobin A1c remains below 7%, continue the current regimen. If it is 7% or higher, consider introducing Glucagon-like peptide-1 receptor agonists (GLP1 RA) or Sodium-glucose co-transporter-2 inhibitors (SGLT-2i), particularly for patients with increased risk of atherosclerotic cardiovascular disease, heart failure, or chronic kidney disease.For individuals presenting with a hemoglobin A1c of 10% or higher, initiate treatment with basal insulin and possibly add GLP1 RA or mealtime insulin as needed. Encourage lifestyle adjustments, and maintain the same follow-up regimen as for other diabetic patients, adding SGLT-2i based on specific cardiovascular or renal risks.Here’s a concise outline:1. **Initial Assessment**: - Determine if the patient is **unstable** or **stable**. - Unstable patients may exhibit severe complications such as hyperosmolar hyperglycemic state (HHS) or diabetic ketoacidosis (DKA). Immediate management includes **IV fluid resuscitation, electrolyte replenishment, and possibly an IV insulin drip**, alongside treating any underlying causes. - Conduct tests including **hemoglobin A1c, random blood glucose, fasting blood glucose, and an oral glucose tolerance test (OGTT)**. - A diagnosis of **diabetes mellitus** is made if: - Fasting blood glucose ≥ 126 mg/dL, - Random blood glucose ≥ 200 mg/dL, or - 2-hour OGTT glucose ≥ 200 mg/dL. - Order **GAD65 antibodies, ICA2 antibodies, and C-peptide levels** to distinguish between type 1 and type 2 diabetes mellitus. The presence of type 2 is indicated by **negative GAD65 and ICA2 antibodies, and normal C-peptide levels**. - For hemoglobin A1c between **6.5% and 10%**: - Start **metformin** and advise lifestyle changes. - Schedule follow-ups every **3 months** to monitor hemoglobin A1c, and annual screenings for **retinopathy, neuropathy, and nephropathy**. - If the initial response to therapy is inadequate, consider adding **GLP1 RA** and **SGLT-2i**, particularly if there are risk factors for ASCVD, heart failure, or chronic kidney disease. - For hemoglobin A1c > 10%, initiate **basal insulin** and consider adding **GLP1 RA**. - Add **short-acting insulin before meals** if necessary. - Continue with lifestyle modifications, regular follow-ups, and consider **SGLT-2i** based on risk assessments."Diabetes Mellitus Type 2" StatPearls Publishing (Updated 2022 Jun 19)"Pathophysiology of Type 2 Diabetes Mellitus" International Journal of Molecular Sciences (2020)"10. Cardiovascular Disease and Risk Management: Standards of Medical Care in Diabetes—2022" Diabetes Care (2021)"Management of hyperglycaemia in type 2 diabetes, 2022. A consensus report by the American Diabetes Association (ADA) and the European Association for the Study of Diabetes (EASD)" Diabetologia (2022)"Standards of Medical Care in Diabetes" Diabetes Care (2022)"Oral Pharmacologic Treatment of Type 2 Diabetes Mellitus: A Clinical Practice Guideline Update From the American College of Physicians" Annals of Internal Medicine (2017) - - - - - - - END - - - - - - -
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