What are the recommended lifestyle modifications and treatment options for an adult patient with prediabetes (impaired fasting glucose or impaired glucose tolerance)?

Management of Prediabetes

Adults with prediabetes should be referred to an intensive lifestyle behavior change program targeting at least 7% weight loss and 150 minutes weekly of moderate-intensity physical activity, with metformin added for those with BMI ≥35 kg/m², age <60 years, fasting glucose ≥110 mg/dL, A1C ≥6.0%, or prior gestational diabetes. 1

Lifestyle Intervention: The Foundation

The Diabetes Prevention Program (DPP) provides the strongest evidence for diabetes prevention in the U.S., demonstrating a 58% reduction in diabetes incidence over 3 years with intensive lifestyle intervention—far superior to any pharmacologic approach. 1 Long-term follow-up confirms durability: 39% risk reduction at 30 years (Da Qing study), 43% at 7 years (Finnish DPS), and 27% at 15 years (DPPOS). 1

Weight Loss Goals

• Target minimum 7% body weight reduction from baseline, achieved through calorie restriction of 500-1,000 calories daily below maintenance needs. 1, 2
• Weight loss of 7-10% provides even greater benefit for diabetes prevention. 1
• Aim for 1-2 pounds per week weight loss rate. 1, 2
• Initial focus can be on reducing total dietary fat, then transition to comprehensive calorie and fat restriction after several weeks. 1

Physical Activity Requirements

• Prescribe at least 150 minutes per week of moderate-intensity aerobic activity (equivalent to brisk walking), distributed over at least 3 days with no more than 2 consecutive days without exercise. 1, 2, 3
• Each session should last at least 10 minutes. 1
• Up to 75 minutes of strength training can count toward the 150-minute weekly goal. 1
• This activity level approximates 700 kcal/week energy expenditure. 1

Dietary Patterns

Multiple eating patterns are effective for diabetes prevention—choose based on patient preference and cultural context. 1 Evidence supports: 1, 4

• Mediterranean-style diet 1, 4
• Low-carbohydrate eating plans 1
• Vegetarian or plant-based diets (may include some animal products) 1, 4
• DASH (Dietary Approaches to Stop Hypertension) 1, 4
• Intermittent fasting 1

All patterns should emphasize whole grains, legumes, nuts, fruits, and vegetables while minimizing refined and processed foods. 1, 4 Eliminate or drastically reduce sugar-sweetened beverages, refined grains, sweets, and ultraprocessed foods. 2

Structured Program Enrollment

Enroll patients in a CDC-recognized Diabetes Prevention Program or equivalent intensive behavioral counseling program. 2 These structured programs provide: 1

• 16-session core curriculum completed within 24 weeks
• Training in self-monitoring techniques
• Guidance on managing psychological, social, and motivational challenges
• Ongoing support for maintaining healthy behaviors

Technology-assisted programs (smartphone apps, web-based platforms, telehealth) are acceptable alternatives, particularly for patients in rural locations or with access barriers, though not all are equally effective. 1

Medical Nutrition Therapy

Refer all patients with prediabetes to a registered dietitian nutritionist (RDN) for individualized medical nutrition therapy at diagnosis and at regular intervals. 1, 2 Medical nutrition therapy achieves significant reductions in weight, waist circumference, and glycemia. 1, 2

Pharmacologic Intervention

Metformin: First-Line Medication

Consider metformin for patients meeting ANY of these high-risk criteria: 1, 2

• BMI ≥35 kg/m²
• Age 25-59 years (particularly <60 years)
• Fasting plasma glucose ≥110 mg/dL
• A1C ≥6.0%
• History of gestational diabetes mellitus

Metformin reduces diabetes incidence by 31% relative risk reduction and has demonstrated long-term safety. 2, 5 However, it is less effective than intensive lifestyle intervention (31% vs 58% risk reduction). 5

Important caveat: Long-term metformin use may cause vitamin B12 deficiency. 1 Periodically assess vitamin B12 levels, especially in patients with anemia or peripheral neuropathy. 1

Alternative Pharmacologic Options

While metformin has the strongest evidence base, other agents have shown efficacy in specific contexts:

• Pioglitazone may be considered for patients with prior stroke and insulin resistance, but balance this against increased risks of weight gain, edema, and fractures. 1 Lower doses may mitigate adverse effects but reduce efficacy. 1
• GLP-1 receptor agonists can achieve significant weight reduction, particularly in patients with obesity. 6
• Acarbose has demonstrated ability to delay diabetes onset. 7, 8

Vitamin D: Insufficient Evidence

Recent meta-analyses suggest modest potential benefit of vitamin D supplementation in specific populations, but several concerns preclude routine recommendation: 1

• Optimal dosing remains unclear (trials used varying doses higher than recommended daily allowance)
• Benefit-to-risk ratio uncertain for widespread use
• Individual trial results were not statistically significant
• Further research needed to define appropriate patient characteristics

Monitoring and Follow-Up

Glucose Monitoring

• Screen for diabetes progression at least annually using fasting glucose, 2-hour oral glucose tolerance test, or A1C. 6, 2
• For patients on interventions, assess response with A1C every 3 months initially. 6

Cardiovascular Risk Management

Patients with prediabetes have increased cardiovascular disease risk and require aggressive cardiovascular risk factor management. 6, 2

• Target blood pressure <140/90 mmHg. 6
• Initiate statin therapy based on cardiovascular risk assessment. 6
• Consider SGLT2 inhibitors or GLP-1 agonists for cardioprotection in appropriate patients. 6
• Screen for chronic kidney disease, atherosclerotic cardiovascular disease, and heart failure. 6

Comprehensive Metabolic Monitoring

• BMI and blood pressure at each visit 6
• Lipid panel annually 6
• eGFR and comprehensive metabolic panel annually 6

Sleep Assessment

Address sleep quality and duration, as sleep deprivation (<6 hours) or excessive sleep (>9 hours) increases diabetes risk by up to 50%. 4 Target 7 hours of sleep per night, which is associated with lowest diabetes risk. 4

Common Pitfalls to Avoid

1. Don't rely solely on A1C for diagnosis in patients with hemoglobinopathies or conditions affecting red blood cell turnover—use fasting glucose or oral glucose tolerance testing instead. 1

2. Don't prescribe metformin without considering high-risk criteria—it's most effective in specific subgroups (younger patients, higher BMI, higher baseline glucose). 1, 2, 5

3. Don't neglect vitamin B12 monitoring in patients on long-term metformin—deficiency can cause irreversible neurologic complications. 1

4. Don't offer lifestyle counseling without structured program referral—unstructured advice is far less effective than intensive, goal-based programs with ongoing support. 1, 2

5. Don't focus exclusively on glucose control while ignoring cardiovascular risk factors—prediabetes increases cardiovascular event rates and mortality. 6, 2, 5