Hypoglycemia

Hypoglycemia is low blood sugar, which ACSM defines as blood glucose below 70 mg/dL.^{1Ozemek et al., ACSM’s Guidelines for Exercise Testing and Prescription, 12th ed., p. 665.} ACSM treats it as a relative contraindication to starting exercise.^{1Ozemek et al., ACSM’s Guidelines for Exercise Testing and Prescription, 12th ed., p. 665.} The NSCA calls it the principal exercise risk for clients with diabetes, with greater concern in type 1 than type 2 diabetes.^{2Schoenfeld and Snarr (eds.), NSCA’s Essentials of Personal Training, 3rd ed., p. 552.} Exercise increases absorption of injected insulin and muscle uptake of glucose while impairing glucose mobilization.^{2Schoenfeld and Snarr (eds.), NSCA’s Essentials of Personal Training, 3rd ed., p. 552.}

Glucose can fall fast enough to cause symptoms above 70 mg/dL, while some clients feel no symptoms at all, called hypoglycemic unawareness.^{1Ozemek et al., ACSM’s Guidelines for Exercise Testing and Prescription, 12th ed., p. 665.} Common symptoms include shakiness, weakness, sweating, anxiety and hunger; more severe symptoms include headache, visual disturbances, confusion, seizures and coma.^{1Ozemek et al., ACSM’s Guidelines for Exercise Testing and Prescription, 12th ed., p. 665.} Risk is higher during and immediately after moderate-intensity aerobic exercise and can last 12 hours or more.^{1Ozemek et al., ACSM’s Guidelines for Exercise Testing and Prescription, 12th ed., p. 665.}

In practice

• The NSCA’s response protocol starts with considering a call to emergency services and checking glucose if a monitor is available.^{3Schoenfeld and Snarr (eds.), NSCA’s Essentials of Personal Training, 3rd ed., p. 553.} If the reading is under 70 mg/dL, or a client with known diabetes shows symptoms, it calls for 15 g of carbohydrate: three or four glucose tablets, half a cup of juice or regular soda, or a tablespoon of sugar or honey.^{3Schoenfeld and Snarr (eds.), NSCA’s Essentials of Personal Training, 3rd ed., p. 553.} Wait about 15 minutes, recheck, and repeat until glucose is above 70 mg/dL.^{3Schoenfeld and Snarr (eds.), NSCA’s Essentials of Personal Training, 3rd ed., p. 553.}
• Clients starting below 100 mg/dL are at risk during or after exercise and should eat a carbohydrate-rich snack first.^{3Schoenfeld and Snarr (eds.), NSCA’s Essentials of Personal Training, 3rd ed., p. 553.} IPTA also advises keeping a snack on hand during exercise.^{4International Personal Trainer Academy, Certified Personal Trainer Textbook, p. 437.}
• Insulin and meal timing advice are outside a trainer’s scope of practice; refer clients with regular lapses in glucose control to their physician.^{3Schoenfeld and Snarr (eds.), NSCA’s Essentials of Personal Training, 3rd ed., p. 553.}
• Clients with diabetes should wear a visible medical alert bracelet.^{3Schoenfeld and Snarr (eds.), NSCA’s Essentials of Personal Training, 3rd ed., p. 553.}

Glucose thresholds

The NSCA’s personal training text defines hypoglycemia as 65 mg/dL or lower, while ACSM uses below 70 mg/dL.^{2Schoenfeld and Snarr (eds.), NSCA’s Essentials of Personal Training, 3rd ed., p. 552.},^{1Ozemek et al., ACSM’s Guidelines for Exercise Testing and Prescription, 12th ed., p. 665.} The NSCA’s response protocol also acts at 70 mg/dL.^{3Schoenfeld and Snarr (eds.), NSCA’s Essentials of Personal Training, 3rd ed., p. 553.}