What are the recommendations for diagnosis and management of Type 1 Diabetes Mellitus (Type 1 DM)?

Diagnosis and Management of Type 1 Diabetes Mellitus

Diagnosis

Type 1 diabetes is diagnosed by demonstrating hyperglycemia (fasting plasma glucose ≥126 mg/dL, random glucose ≥200 mg/dL with symptoms, or 2-hour OGTT ≥200 mg/dL) or HbA1c ≥6.5%, often in the context of acute presentation with ketosis or diabetic ketoacidosis. 1

• The diagnosis should be confirmed prior to initiating insulin therapy 2
• Type 1 diabetes results from autoimmune destruction of pancreatic β-cells, rendering patients unable to synthesize insulin 1
• Consider screening for autoimmune thyroid disease with thyroid autoantibodies at the time of diabetes diagnosis, given high prevalence of concurrent autoimmune conditions 3
• Screen for other autoimmune diseases including celiac disease in patients with type 1 diabetes 4, 3

Insulin Therapy: The Cornerstone of Treatment

All patients with type 1 diabetes require insulin therapy from diagnosis, with multiple daily injections (MDI) of basal and prandial insulin (3-4 injections daily) or continuous subcutaneous insulin infusion (CSII/pump therapy) as the standard of care. 1, 4, 2

Initial Insulin Regimen

• Start with total daily insulin dose of 0.4-1.0 units/kg/day (typically 0.5 units/kg for metabolically stable patients) 3
• Distribute approximately 30-50% as basal insulin and the remainder as prandial insulin 3
• Basal insulin is given once or twice daily using intermediate or long-acting insulin 2
• Prandial insulin is given 0-15 minutes before meals using short-acting or rapid-acting insulin analogues 2

Insulin Type Selection

Use insulin analogues rather than human insulins to reduce hypoglycemia risk, particularly nocturnal hypoglycemia. 1, 4, 3

• Long-acting basal analogues have reduced peak profiles, extended duration of action, and lower intraindividual variability compared to NPH insulin 5
• Rapid-acting prandial analogues (aspart, glulisine, lispro) are preferred over regular human insulin for better postprandial glucose control 5
• Insulin analogues match the A1C lowering of human insulins while reducing severe hypoglycemia rates (the DCCT showed 62 episodes per 100 patient-years with human insulins) 1

Insulin Delivery Methods

• MDI and CSII show no systematic differences in A1C or severe hypoglycemia rates in meta-analyses 1
• Consider sensor-augmented insulin pump therapy with threshold-suspend feature for patients with nocturnal hypoglycemia, as this reduces nocturnal hypoglycemia without increasing HbA1c 1, 3
• Pump therapy may be preferred for patients not meeting glycemic targets, those with frequent/severe hypoglycemia, or pronounced dawn phenomenon 5
• The shortest needles (4-mm pen, 6-mm syringe) are safe, effective, less painful, and should be first-line choice to avoid intramuscular injections 2

Patient Education Requirements

All patients must receive diabetes self-management education on matching prandial insulin doses to carbohydrate intake, premeal blood glucose levels, and anticipated physical activity. 1, 4, 3

• Education should include problem-solving skills for all aspects of diabetes management 4
• Teach carbohydrate counting as the foundation for prandial insulin dosing 1, 5
• For advanced patients who have mastered carbohydrate counting, incorporate education on the impact of protein and fat on glycemic excursions 1
• Educate on recognition and management of hypoglycemia (treat with 15-20g rapid-acting glucose, recheck in 15 minutes, repeat if needed) 4, 3
• Patients should perform frequent blood glucose measurements and adjust insulin dosing based on multiple parameters including physical activity, meal timing, illness, and circadian rhythm 5, 6

Glucose Monitoring

Real-time continuous glucose monitoring (rt-CGM) should be used in conjunction with insulin in teens and adults with type 1 diabetes who are not meeting glycemic targets, have hypoglycemia unawareness, and/or episodes of hypoglycemia. 1

• rt-CGM leads to lower HbA1c and reduced time in hypoglycemic range in adults with type 1 diabetes 1
• In adults over age 60 with type 1 diabetes, rt-CGM significantly reduces both time in hypoglycemia and severe hypoglycemic events 1
• Consider intermittently scanned CGM (is-CGM) as an alternative to lower HbA1c and/or reduce hypoglycemia in adults with type 1 diabetes 1
• For children with type 1 diabetes, consider rt-CGM or is-CGM based on regulatory approval to improve glucose control and reduce hypoglycemia risk 1
• Unless CGM is used, patients on multiple daily insulin injections should perform blood glucose monitoring at least 4 times daily 1
• Consistency of CGM use is highly correlated with lower HbA1c; adolescents and young adults require considerable education and support for optimal CGM adherence 1

Glycemic Targets

Target HbA1c <7% (53 mmol/mol) for most nonpregnant adults with type 1 diabetes to reduce microvascular complications by 50% and reduce macrovascular complications. 4, 3, 5

• For children with type 1 diabetes, including preschool children, target HbA1c <7.5% (58 mmol/mol) to minimize hyperglycemia, severe hypoglycemia, and long-term complications 2
• Individualize targets based on duration of diabetes, age/life expectancy, known cardiovascular disease, hypoglycemia unawareness, and individual patient considerations 4
• Use fasting plasma glucose values to titrate basal insulin; use both fasting and postprandial glucose values to titrate mealtime insulin 2

Ketone Monitoring

Individuals with type 1 diabetes should measure ketones in urine or blood if they have unexplained hyperglycemia or symptoms of ketosis (abdominal pain, nausea) and implement sick-day rules. 1

• Patients with type 1 diabetes are prone to ketosis and diabetic ketoacidosis 1
• Ketone testing is essential during acute illness or periods of metabolic stress 1

Screening for Complications

Regularly screen for diabetes complications including retinopathy, nephropathy, neuropathy, and cardiovascular disease. 4

• Measure thyroid-stimulating hormone (TSH) after metabolic control is established, then recheck every 1-2 years or sooner if symptoms develop 3
• Screen for celiac disease and other autoimmune conditions common in type 1 diabetes 4, 3
• Perform age- and sex-appropriate cancer screenings 4

Adjunctive Therapy

• Individualized medical nutrition therapy provided by a registered dietitian is recommended 4
• Physical activity recommendations include at least 150 minutes of moderate-intensity aerobic activity per week, reduced sedentary time, and resistance training at least twice weekly 4
• Consider metformin combined with insulin in appropriate patients, as it is associated with decreased weight gain, lower insulin dose, and less hypoglycemia compared to insulin alone 2

Critical Pitfalls to Avoid

• Never use sliding-scale insulin alone as the sole insulin regimen—this approach is strongly discouraged 4
• Avoid therapeutic inertia; prioritize timely intensification of therapy when targets are not met 4
• Do not aggressively pursue near-normal HbA1c in patients where such targets cannot be safely achieved due to hypoglycemia risk 4
• For patients with hypoglycemia unawareness, temporarily increase glycemic targets to help reverse the condition 4
• Severe or frequent hypoglycemia is an absolute indication for modification of treatment regimens 4
• Avoid injections into areas of lipohypertrophy, as this distorts insulin absorption; practice correct site rotation 2
• Do not abruptly discontinue other medications when starting insulin therapy due to risk of rebound hyperglycemia 2

Team-Based Care Approach

Utilize a collaborative, integrated team with expertise in diabetes including physicians, nurse practitioners, physician assistants, nurses, dietitians, pharmacists, and mental health professionals. 4

• Care should align with the Chronic Care Model, which has been shown to reduce cardiovascular disease risk by 56.6%, microvascular complications by 11.9%, and mortality by 66.1% 4
• Treatment decisions should be timely, evidence-based, and incorporate patient preferences, literacy assessment, and cultural considerations 4
• Reassess insulin-taking behavior and treatment plans every 3-6 months 3