Diagnosis and Treatment of Diabetes
Diagnosis
Diabetes is diagnosed through laboratory testing of blood glucose levels, with fasting plasma glucose ≥126 mg/dL, random plasma glucose ≥200 mg/dL with symptoms, 2-hour oral glucose tolerance test ≥200 mg/dL, or HbA1c ≥6.5% being diagnostic criteria.
Key diagnostic parameters to assess:
- Fasting plasma glucose: ≥126 mg/dL on two separate occasions confirms diabetes
- HbA1c: ≥6.5% indicates diabetes; provides 2-3 month average glucose control
- Random plasma glucose: ≥200 mg/dL with classic symptoms (polyuria, polydipsia, unexplained weight loss)
- 2-hour oral glucose tolerance test: ≥200 mg/dL after 75g glucose load
Distinguish between Type 1 and Type 2:
- Type 1: Typically younger onset, acute presentation, autoimmune destruction of beta cells, absolute insulin deficiency, prone to ketoacidosis
- Type 2: Typically older onset, gradual presentation, insulin resistance with relative insulin deficiency, associated with obesity (BMI >25-30 kg/m²)
Treatment Options
Type 1 Diabetes
All patients with Type 1 diabetes require insulin therapy from diagnosis, using a basal-bolus regimen with long-acting basal insulin (such as insulin glargine once daily at bedtime) combined with rapid-acting insulin before meals. 1
Insulin regimen specifics:
- Basal insulin: Insulin glargine administered once daily at bedtime provides 24-hour glucose-lowering effect with median duration of 24 hours (range 10.8 to >24 hours) 1
- Bolus insulin: Regular human insulin or rapid-acting analogs (insulin lispro) before each meal 1
- Expected outcomes: HbA1c reduction with baseline values around 7.6-8.5% achieving adjusted mean changes of -0.1 to +0.3% 1
Dosing considerations:
- Typical basal insulin starting dose: 21-29 units daily in adults 1
- Total daily insulin: Approximately 43-51 units in adults with Type 1 diabetes 1
- Pediatric patients (ages 6-15): Basal insulin around 19 units daily, total insulin around 43 units daily 1
Type 2 Diabetes
Treatment begins with lifestyle modifications (diet and exercise), progressing to oral antidiabetic medications, and adding basal insulin (such as insulin glargine once daily at bedtime) when oral agents are insufficient to achieve glycemic control. 1
Treatment progression:
- Initial therapy: Oral antidiabetic medications including metformin (first-line), sulfonylureas, or acarbose, used alone or in combination 1
- Insulin addition: When oral agents fail to achieve target HbA1c, add insulin glargine once daily at bedtime while continuing oral medications 1
- Basal-bolus regimen: For patients not using oral agents or with more advanced disease, use insulin glargine once daily at bedtime with regular human insulin before meals as needed 1
Expected outcomes in Type 2 diabetes:
- HbA1c reduction: Similar effectiveness between insulin glargine and NPH insulin over 28-52 weeks 1
- Fasting glucose improvement: Baseline values around 166-194 mg/dL with reductions of 12-29 mg/dL 1
Special Population Considerations
Pediatric patients (ages 6-15): Higher incidence of severe symptomatic hypoglycemia compared to adults; requires careful monitoring and family education 1
Geriatric patients (≥65 years): Use conservative initial dosing and increments to avoid hypoglycemic reactions, which may be difficult to recognize in this population 1
Renal impairment: Frequent glucose monitoring and dosage adjustments necessary due to increased circulating insulin levels 1
Hepatic impairment: Frequent glucose monitoring and dosage adjustments necessary 1
Critical Monitoring Parameters
- HbA1c: Every 3 months to assess long-term glycemic control
- Fasting blood glucose: Daily self-monitoring
- Hypoglycemia recognition: Mild episodes treated with oral carbohydrates; severe episodes with coma, seizure, or neurologic impairment require glucagon or concentrated intravenous glucose 1
- Hypokalemia: Monitor and correct appropriately with insulin therapy 1