Adjustment of Insulin Dosage
The management of diabetes is usually based on a 24-hour medication schedule. When traveling north or south, no adjustments in the 24-hour schedule are needed. However, east or west travel across time zones extends or abbreviates the day, depending on the direction of travel. When five or fewer time zones are crossed, no change is required in the usual insulin routine. When crossing six or more time zones, however, adjustment in the usual schedule is advisable.

The timing of oral diabetes medication is not as critical as that of insulin. People taking pills for their diabetes should simply take their medicines at the prescribed time using local time.

Frequent blood glucose monitoring is essential for safety. In addition to the typical measurements before breakfast and dinner, travelers should check blood glucose levels whenever their daily routine is disrupted. Even individuals normally lax about home glucose monitoring should test at least twice daily while traveling. When in doubt, measure. If the person feels even slightly ill, blood glucose should be measured.

Traveling East Across Six or More Time Zones
One Dose Schedule
Individuals who normally take insulin once daily before breakfast should take the usual dose at the usual time on the day of departure (Table 2). Meals provided in-flight will usually suffice but supplemental snacks may be necessary if meals are delayed. Leaving the wristwatch unadjusted during flight so that it continues to correspond to the time at the point of departure will make it easier to judge whether there is an undue delay between meals.

The first morning at the destination, just before breakfast (local time), two-thirds of the usual morning dose of NPH or Lente (NPH/L) is taken since fewer than 24 hours will have elapsed since the previous morning’s insulin injection. This reduced dose is designed to prevent hypoglycemia early in the day, particularly under circumstances that may involve extra activity or disruption of meal schedules. The usual doses of Regular or Humalog (R/H) are taken with meals.

To protect against an elevation in blood glucose as a result of the reduced morning dose, blood glucose should be tested before dinner that evening; that is, about 10 hours after the morning insulin dose.

If the blood glucose level is 240 mg/dl or less, no further insulin is needed until the next morning. If the blood glucose is greater than 240 mg/dl, the remaining one-third of the usual N/L insulin dose that was omitted that morning should be taken. The usual insulin dose is resumed beginning the morning of the second day at the destination.

Two Dose Schedule
People who customarily take two insulin injections daily will give the usual morning and evening doses the day of departure. They will also administer only two-thirds of their usual morning dose of NPH or Lente insulin the first morning at the destination (Table 2). That evening, if a blood test for glucose before dinner shows 240 mg/dl or less, they simply take their usual evening dose of insulin. However, if the blood glucose is greater than 240 mg/dl, they should add to their evening dose the one-third of the morning dose of NPH or Lente that was omitted.

"Practicing internal medicine allows me to see a diverse population of people with a variety of medical problems. It is a privilege to get to know my patients well and follow them over the years."

Those who take Ultra-Lente (UL) insulin should follow directions of the one or two dose schedule as appropriate. Plus, take the normal doses of Regular and Humalog (R/H) at actual meal times.

Insulin Pump
Those who have continuous infusion with insulin pumps should leave settings as is and change the clock on the pump when they arrive at their destination. Boluses follow usual rules.

TABLE 2:
Insulin Adjustment When Traveling East Across Multiple Time Zones

Traveling West Across Six or More Time Zones
One Dose Schedule
On the day of departure, the usual morning dose of insulin is taken before breakfast (Table 3). In flight, meals are eaten at the times provided for other passengers. It is advisable to check blood glucose before meals or at 6-hour intervals during the flight. The usual doses of Regular or Humalog (R/H) are taken with meals. About 18 hours after the morning insulin injection, whether still in flight or at the destination, the blood glucose should be tested. If the blood glucose is 240 mg/dl or less, the individual may safely wait until the first morning at the destination to take the usual insulin dose at the usual time (local time), even though more than 24 hours will have elapsed. However, if the blood glucose level is greater than 240 mg/dl, a supplemental dose of insulin equal to one-third of the usual morning dose of NPH or Lente should be taken followed by a meal or snack. For example, if the usual morning dose is 30 units of Lente plus 12 units of Regular insulin, the supplemental dose is 10 units Lente plus 12 units of Regular. The next morning (local time), the usual insulin dose is taken.

Two dose schedule
Patients who normally take insulin on a twice-daily schedule should leave their wristwatches unadjusted during the flight. They should take their usual morning dose. Then, at about the time of the evening meal at the point of departure (i.e., about 10-12 hours after the morning dose of insulin), the usual second insulin dose is taken, followed by a meal or snack (Table 3). From that time on, they follow the same plan as travelers who take one injection daily. Thus, at about 18 hours after the first dose of insulin and 6 hours after the second, the blood is tested and if the blood glucose is more than 240 mg/dl an extra dose of insulin equal to one third of the morning dose of NPH or Lente is taken.

Those who take Ultra-Lente (UL) should follow directions of one or two dose schedule as appropriate. Plus take Regular and Humalog (R/H) at actual meal times.

Insulin Pump
Those who have continuous infusion with insulin pumps should leave settings as is and change the clock on the pump when they arrive at their destination. Boluses follow usual rules.

TABLE 3:
Insulin Adjustment When Traveling West Across Multiple Time Zones

Prevention of Hypoglycemia
Travel usually involves a drastic departure from daily routine. Meals may be delayed or unavailable. Physical activity is often greatly increased. These factors increase the risk of hypoglycemia. The principle of eating extra food when engaged in extra activity becomes especially important when traveling. Suitable snacks such as crackers, dried fruits, or nuts should be carried for use if meals are delayed or to supplement meals if necessary. Sugar cubes or other sources of rapidly absorbed sugar should also be available in case hypoglycemic symptoms develop.

Traveling companions should be advised of the early signs of hypoglycemia and should understand the importance of administering sugar-containing drinks if the person becomes glassy-eyed, confused, irritable, or is noted to be sweating inappropriately. If the person is too confused to swallow, food or fluid should not be administered. Glucagon, if available, should be administered by injection.¹ Skilled medical care should be obtained without delay for stuporous or unconscious individuals.

General Precautions
All persons taking medicines for diabetes, whether insulin or pills, should wear a necklace or bracelet to identify themselves as having diabetes. Those whose diabetes is controlled with diet alone should not wear identification, to avoid confusion should the individual be found unconscious.

It is usually advisable for persons with diabetes to see their physicians shortly before departure. This visit should be used not only to discuss diabetes care but also to evaluate other known or suspected health problems. The feet of travelers with diabetes are especially vulnerable to injury and infection.² The traveler should be aware of the dangers of producing blisters by extended walking, particularly in new shoes. Any sign of infection of the feet mandates a visit to a physician.

Obtaining Medical Assistance
The names of English-speaking physicians practicing in foreign countries can be obtained by writing to the International Association of Medical Assistance to Travelers (IAMAT), 417 Center Street, Lewiston, NY 14092, (716) 754-4883, E-mail: iamat@sentex.net or by contacting a local United States embassy (IAMAT Web page). Emergency aid is usually best obtained at the emergency room of a university hospital.

Of Special Notice
Development of minor illnesses should lead to steps to prevent ketoacidosis. Additional insulin coverage, or following rules for sick days, may be required.4 In non-emergency circumstances, the best means of obtaining proper medical advice may well be a telephone call to the individual’s own physician back home. The cost of a long-distance call from anywhere in the world is usually less than the cost of even the most minor medical care, and calling the physician who knows the patient best is usually money well spent. In addition, the physician may know of a reliable colleague located within reachable distance.

References

1. Hypoglycemia: Recognition, Prevention, and Treatment. Available from the Section of Endocrinology and Metabolism, Virginia Mason Medical Center, PO Box 900, Seattle WA 98111.
   
2. Foot Care for People with Diabetes. Available from the Section of Endocrinology and Metabolism, Virginia Mason Medical Center, PO Box 900, Seattle, WA 98111
   
3. Gortner DA. Advice for international travelers - 1984. Bulletin Mason Clinic summer 1984; 38:55-56.
   
4. Care During Illness: Prevent Ketoacidosis. Available from Section of Endocrinology and Metabolism, Virginia Mason Medical Center, PO Box 900, Seattle, WA 98111.

Reprinted with permission of: EDWARD A. BENSON, MD