Travelling east-west or west-east across time zones makes eating and injecting insulin at the right time a more complicated business. Do you go by the time in your place of departure or your place of arrival when deciding when to inject? What is the best way of changing over from one to the other?

When there is a time difference between your departure point and your destination, using the local time to decide when meals and injections are due will make the time between some of your injections much longer or shorter than usual. This can cause you to have too little or too much insulin on board, so there is a risk of your blood glucose level rising or falling dramatically.

There are several ways around this, and the methods given below are just a starting point. You should discuss your plans with your diabetes care team at an early stage so that they can support you in working out how best to manage your blood sugars when travelling.

If you are on a “basal/bolus” insulin regimen i.e. you inject quick-acting insulin at each meal and long-acting insulin once a day

Rapid and Quick acting insulins

(e.g.  insulin aspart (Novorapid®), insulin lispro (Humalog®), insulin glulisine (Apidra®), insulin aspart (Trurapi®. FiAsp®). Actrapid®, Humulin® S and Insuman Rapid®)

	East to West If you are flying westwards, e.g. from London to Mexico City, the time difference of six hours will make the day six hours longer. Because of this you may find you are eating an additional meal. You should simply inject your quick-acting insulin and eat as usual.
	West to East If you are flying eastwards, e.g. Mexico City to London, the time difference of six hours will make the day six hours shorter. Because of this you will probably be having one less meal on your day of travel so you will need one less injection of quick-acting insulin. You should continue to take your long-acting insulin at the usual times (measured according to local time).

Long acting insulins

(e.g.   insulin detemir (Levemir®), insulin glargine (Abasaglar®, Semglee®, Lantus®, Toujeo®) and insulin degludec (Tresiba®))

If you are only away for short time, you may wish to leave your injection on Saudi Arabia time.

If you are away for longer, you may wish to change the time of your injection. One way to do this is to simply move the injection to a convenient time. If this is longer than 24 hours since your last injection, you may need to give a small dose of short-acting insulin to control blood glucose levels.

If you are on an insulin pump

Insulin Pump You use your pump as normal, remembering to bolus for meals. Change the clock on your pump to the new local time once you arrive at your destination. Don't forget to change it back when you get home!

If you take mixed insulin twice a day

 e.g. Humulin M3, Mixtard 30/70, NovoMix30

East to West If you are flying westwards, e.g London to Mexico City, you could take your usual two injections per day plus an extra injection of quick-acting insulin (supplied by your clinic) eight to ten hours after your first injection of the day. This would be just before the time of your usual third meal. Take your next dose of mixed insulin with your fourth meal. This way you will be taking four meals plus snacks on that day, but the time difference will lengthen the day by six hours.

West to East If you are flying eastwards eg Mexico City to London, you could miss your second injection of mixed insulin and instead take an injection of quick-acting insulin (supplied by your clinic). The dose will be about the same as the quick-acting component of your usual mixture. You would then only be having two meals plus snacks on that day, but the day would be six hours shorter because of the time difference.

General points

• Remember to eat after taking quick-acting insulin (or mixtures containing quick-acting insulin) even if that means eating an extra meal one day.
• Check your blood glucose levels frequently when you are changing time zones.
• Discuss the details of how you will take your insulin with your diabetes care team before you go.
• If the time difference between your departure point and your destination is less than three hours you should be able to stick to your usual insulin regimen.
• Make sure your meals are eaten four to six hours apart.
• Ask the airline when the in-flight meals will be served and use them as between-meal snacks or as proper meals, whichever fits your schedule better. You can use your own food to add to what is served or ask for a few extra bread rolls – there are usually some to spare.
• Remember that drinking alcohol on a flight will affect your blood glucose
• If flying makes you feel stressed, this will affect your blood glucose too.
• If you are usually quite active, there is a limit to how much energy you can burn up in an airline seat, so doing nothing may give you a higher blood glucose level if everything else remains the same.
• Take some extra food in your hand luggage in case of unexpected delays.