What are the typical diagnosis and treatment options for diabetes?

Diagnosis and Treatment of Diabetes Mellitus

Diagnostic Criteria

Diabetes is diagnosed when any of the following criteria are met: A1C ≥6.5%, fasting plasma glucose ≥126 mg/dL, 2-hour plasma glucose ≥200 mg/dL during 75-g OGTT, or random glucose ≥200 mg/dL with classic hyperglycemic symptoms (polyuria, polydipsia, unexplained weight loss). 1

Confirmation Requirements

• If plasma glucose alone indicates diabetic type, re-examination on another day is required to confirm the diagnosis 2
• If both plasma glucose (any criterion) AND A1C ≥6.5% are elevated in the same blood sample, diabetes can be diagnosed immediately without repeat testing 2, 1
• Diagnosis can be made at initial visit if plasma glucose indicates diabetic type AND either classic symptoms or definite diabetic retinopathy are present 2

Specific Diagnostic Thresholds

• Fasting plasma glucose ≥126 mg/dL (no caloric intake for ≥8 hours) 1
• 2-hour plasma glucose ≥200 mg/dL during 75-g OGTT 1
• Random plasma glucose ≥200 mg/dL with classic symptoms or hyperglycemic crisis 1
• A1C ≥6.5% (must be NGSP certified and standardized to DCCT assay) 1

Important caveat: A1C alone cannot be used for re-examination to confirm diabetes; plasma glucose must also indicate diabetic type when using A1C for diagnosis. 2

Screening Recommendations

Screen all adults ≥35 years of age for prediabetes and diabetes. 1

High-Risk Populations Requiring Earlier Screening

Screen adults with BMI ≥25 kg/m² who have one or more of the following risk factors: 1

• Physical inactivity
• First-degree relative with diabetes
• High-risk ethnicity (African American, Latino, Native American, Asian American, Pacific Islander)
• History of gestational diabetes
• Hypertension (≥140/90 mmHg or on therapy)
• HDL cholesterol <35 mg/dL or triglycerides >250 mg/dL
• Polycystic ovary syndrome
• A1C ≥5.7%, impaired glucose tolerance, or impaired fasting glucose on previous testing

Repeat screening every 3 years if results are normal. 1

Treatment Approach for Type 2 Diabetes

Initial Management

Newly diagnosed overweight or obese patients should begin lifestyle modifications (physical activity, weight loss of at least 5%) and metformin at or soon after diagnosis if lifestyle efforts are insufficient to maintain glycemic goals. 2

Metformin is the preferred initial pharmacologic agent (A rating). 2

Glycemic Targets

The A1C goal for most nonpregnant adults is <7%. 2

More stringent A1C goals (such as <6.5%) may be appropriate for selected patients with: 2

• Short duration of diabetes
• Type 2 diabetes treated with lifestyle or metformin only
• Long life expectancy
• No cardiovascular disease

Less stringent A1C goals (such as <8%) are appropriate for patients with: 2

• History of severe hypoglycemia
• Limited life expectancy
• Advanced microvascular or macrovascular complications
• Extensive comorbid conditions
• Long-standing diabetes with difficulty achieving goals despite intensive efforts

Monitoring

A1C testing should be performed at least twice yearly in patients meeting treatment goals with stable glycemic control. 2

A1C testing should be performed quarterly in patients whose therapy has changed or who are not meeting glycemic goals. 2

Patients on intensive insulin regimens (≥3 injections daily or insulin pump) should perform self-monitoring of blood glucose before meals and snacks, occasionally postprandially, at bedtime, before exercise, when suspecting low glucose, and before critical tasks such as driving. 2

Pharmacologic Treatment Algorithm for Type 2 Diabetes

When Metformin Monotherapy is Insufficient

If A1C remains above target on metformin, add a second agent from the following classes based on patient-specific factors: 2

• Sulfonylureas - effective but increase hypoglycemia risk
• DPP-4 inhibitors - weight neutral, low hypoglycemia risk
• GLP-1 receptor agonists - promote weight loss, low hypoglycemia risk
• SGLT2 inhibitors - promote weight loss, low hypoglycemia risk, but FDA warning for ketoacidosis risk 2
• Thiazolidinediones (pioglitazone) - use with caution in patients with or at risk for heart failure; associated with fractures and weight gain 2
• Basal insulin - most effective for lowering glucose but increases hypoglycemia risk and weight gain

When to Initiate Insulin

Consider dual therapy with metformin plus basal insulin when A1C is ≥9%. 2

Consider triple therapy or basal insulin plus mealtime insulin when blood glucose is 300-350 mg/dL or greater and/or A1C is 10-12%, especially if symptomatic or catabolic features (unintentional weight loss, ketosis) are present. 2

Insulin should be used immediately in newly diagnosed patients when severe hyperglycemia causes ketosis or unintentional weight loss (E rating). 2

Insulin therapy should not be delayed in patients not achieving glycemic goals (B rating). 2

Insulin Initiation and Titration

Basal insulin may be initiated at 10 units or 0.1-0.2 units/kg body weight. 2

Basal insulin is typically used with metformin and perhaps one additional noninsulin agent. 2

When basal insulin has been titrated to appropriate fasting blood glucose levels but A1C remains above target, add either a GLP-1 receptor agonist or prandial insulin (1-3 injections of rapid-acting insulin immediately before meals). 2

Insulin analogues are preferred for bolus insulin because they are faster-acting. 2

Medication Management with Complex Insulin Regimens

When more complicated insulin regimens (beyond basal insulin) are used, sulfonylureas, DPP-4 inhibitors, and GLP-1 receptor agonists are usually withdrawn. 2

Thiazolidinediones or SGLT2 inhibitors may be continued to improve glucose control and reduce total daily insulin dose, but thiazolidinediones should be used with caution in patients with or at risk for congestive heart failure. 2

Treatment Approach for Type 1 Diabetes

Most patients with type 1 diabetes should be treated with multiple-dose insulin injections (≥3 injections daily) or continuous subcutaneous insulin infusion (A rating). 2

Patients should use insulin analogues to reduce hypoglycemia risk (A rating). 2

Patients should be educated on matching prandial insulin doses to carbohydrate intake, preprandial blood glucose levels, and anticipated activity level (E rating). 2

Continuous glucose monitoring systems significantly reduce severe hypoglycemia risk in patients with type 1 diabetes. 2

Hypoglycemia Management

Hypoglycemia (plasma glucose <70 mg/dL) should be reversed with 15-20 g of rapid-acting glucose; pure glucose is preferred. 2

Blood glucose should be confirmed with self-monitoring after 15 minutes; if hypoglycemia persists, repeat treatment. 2

Patients at risk for severe hypoglycemia should be prescribed glucagon, and close contacts should be instructed on administration (E rating). 2

Severe or frequent hypoglycemia is an absolute indication for modification of treatment regimens. 2

Cardiovascular Risk Factor Management

Cardiovascular risk factors should be systematically assessed at least annually in all patients with diabetes, including dyslipidemia, hypertension, smoking, family history of premature coronary disease, and presence of albuminuria. 2

Atherosclerotic cardiovascular disease is the leading cause of morbidity and mortality for persons with diabetes; controlling multiple risk factors simultaneously provides large benefits. 2

Foundational Care Elements

All patients should participate in diabetes self-management education and support (B rating). 2

An individualized medical nutrition therapy program, preferably provided by a registered dietitian, is recommended for all persons with diabetes (A rating). 2

Physical activity should include at least 150 minutes of moderate-intensity aerobic activity per week, reduced sedentary time, and resistance training at least twice weekly. 2