1. 
   Blood Glucose Monitoring:
   • Before Exercise: Check blood sugar levels before starting any physical activity. If it’s too low (<70 mg/dL or 3.9 mmol/L), treat hypoglycemia first.
   • During/After Exercise: Intense or prolonged workouts (like 2 hours of gym or boxing) can lower blood glucose significantly. Swimming afterward may further reduce levels, increasing the risk of hypoglycemia—especially if you’re on insulin or certain oral medications (e.g., sulfonylureas).
   • Post-Workout: Continue monitoring for several hours, as delayed hypoglycemia can occur up to 24 hours after intense exercise.
2. Hydration and Nutrition:
   • Stay well-hydrated.
   • Have a small carbohydrate-containing snack before swimming if blood sugar is trending low or if the combined workout duration is long.
   • Carry fast-acting carbs (e.g., glucose tablets) poolside in case of hypoglycemia.
3. Type of Diabetes Matters:
   • Type 1 Diabetes: Requires careful insulin dose adjustments and carb intake planning around exercise.
   • Type 2 Diabetes: May be on medications that increase hypoglycemia risk; others (like metformin) rarely cause lows, but intense exercise can still affect glucose levels.
4. Foot and Skin Care:
   • Diabetics are at higher risk for foot injuries and infections. Ensure proper footwear during gym/boxing and check feet regularly.
   • Public pools can pose infection risks if you have open wounds or neuropathy—take care with hygiene.
5. Listen to Your Body:
   • If you feel dizzy, shaky, excessively fatigued, or confused, stop immediately and check your blood sugar.

Practical Tips:

• Avoid back-to-back intense workouts without adequate recovery and fueling unless you’re experienced and closely monitoring your response.
• Consult your healthcare provider or diabetes educator before starting a new or intensified exercise routine.
• Consider wearing a medical ID bracelet indicating you have diabetes.

Bottom Line: Yes, swimming after a gym or boxing session is possible and even beneficial for cardiovascular health and glucose control—but it must be done mindfully with blood sugar monitoring, proper nutrition, and awareness of hypoglycemia risks.