Upswing: Caffeine

Blood sugar can rise after drinking coffee, even black coffee with no calories,  thanks to the caffeine. Likewise, black tea, green tea, cola and energy drinks can hinder blood sugar control in people with diabetes. Each person reacts differently, so it's best to track your own responses to foods and activities. Ironically, some studies suggest other compounds in coffee may help prevent type 2 diabetes in healthy people, but more research is needed. 

Upswing: Sugar-free foods

Many foods labelled 'sugar free' can raise your blood sugar levels. Why? They can still have plenty of carbs from starches. Check the total carbohydrates on the label before tucking in. You should also pay attention to artificial sweetners or nutritive sweeteners such as sorbitol and xylitol. They add sweetness with fewer carbs than sugar (sucrose), but may still have enough carbs to raise your blood sugar levels.

Upswing: A bad cold

Your blood sugar can rise as your body works to fight off an illness. Drink water and other fluids to stay hydrated. Seek medical advice if you've had diarrhoea or vomiting for more than two hours or if you've been ill for two days and aren't getting better. Some medications, such as antibiotics and the decongestants used to clear your sinuses, can affect your blood sugar.

Upswing: Job stress

Feeling overwhelmed or unhappy at work takes a toll. When you're under stress, your body releases hormones that can cause your blood sugar to rise.  This is more common for people with type 2 diabetes, than those with type 1 diabetes. Learn to relax with deep breathing and exercise. If possible, change the situation that is making you feel so stressed.

Upswing: Bagels

What's the difference between eating a slice of white bread and a bagel? Bagels are packed with carbohydrates and calories. They have more carbs than a slice of bread. If you yearn for a bagel, choose a wholegrain mini bagel or just eat half a normal size bagel. Certain foods may make your blood sugar spike even more than you would expect. Talk with your GP, diabetes nurse, or dietitian to find healthy alternatives.

Upswing: Sports Drinks

Sports drinks are designed to help you replenish fluids quickly, and some of them contain a lot of sugar. For a moderate workout of less than an hour, plain water is probably all you need. For longer, more intense exercise, a sports drink may be appropriate. But check with your GP, diabetes nurse, or dietitian first to see if the calories, carbs and minerals in a particular sports drink are suitable for you.

Upswing: Dried fruits

Fruit is a healthy choice, but dried fruit will pack more carbohydrates in a smaller serving size. Just 2 tablespoons of raisins, dried cranberries or dried cherries have the carbs of a small piece of fruit. Three dates give you 15 grams of carbohydrates.

Upswing: Steroids and water pills

One large family of drugs, corticosteroids such as prednisolone, can cause your blood sugar to rise, and may even trigger diabetes in some people. Steroids can be given to treat certain skin rashes, arthritis, asthma and other conditions. Diuretics used for high blood pressure, called water tablets, can also raise blood sugar levels if you have diabetes. Some antidepressants may raise or lower blood sugar.

Upswing: Cold medicines

Decongestants that contain pseudoephedrine or phenylephrine can raise blood sugar. Cold medicines also sometimes contain sugar or alcohol. Although the sugar content is small, it is best to use products that are sugar-free and alcohol-free. Antihistamines are unlikely to cause a problem with blood sugar. Ask your pharmacist about the possible effects of over-the-counter products before you buy them.

Caution: Contraceptive pills

Women with diabetes can safely use oral contraceptives. Diabetes UK recommends the combined pill and the progestogen-only pill (mini-pill). It also notes that birth control injections and implants are suitable for women with diabetes, and that hormone-releasing IUDs, called intra-uterine systems (IUS) although also suitable, can affect blood sugar levels.

Lower: Housework

Cleaning the house or mowing the lawn can have an added bonus for people with diabetes - lower blood sugar. Many of the jobs you do around the home count as moderate physical activity, with plenty of health benefits. Make a point of walking around the supermarket aisles or parking further from the shops. Small amounts of exercise add up.

Lower: Yoghurt

Foods that contain healthy bacteria, such as many types of yoghurt, are called "probiotic." Some studies suggest they may improve digestion and may help you control blood sugar, but more research is needed. Some yoghurts contain added sugar and fruit, so be careful to count the carbs. Your best choice is natural yoghurt or fat-free yoghurt without added sugar.

Lower: Vegan diet

People with type 2 diabetes who switched to a vegan or entirely vegetable-based diet had better blood sugar control and needed less insulin, according to one study. A boost in fibre from eating wholegrains and beans might play a role by slowing down the digestion of carbs. More research is needed to confirm the value of a vegan diet for diabetes. Talk to your GP, diabetes nurse, or dietitian before making major changes to your diet.

Promising: Cinnamon

Sprinkling your food with cinnamon can add flavour without adding salt, carbs, or calories. Some studies suggest it also can improve the body's ability to use insulin and may lower blood sugar in people with type 2 diabetes. However, such foods are not magic pills for your diabetes diet and more research is needed to confirm these promising studies. Also, supplements containing large doses can cause side effects. So it's best to talk with your GP before trying any supplement.

Caution: Sleep

Blood sugar can dip dangerously low during sleep for some people with type 1 diabetes. It's best to check your blood sugar level at bedtime and when you wake up. A snack before bed may help. For some people, blood sugar can rise in the morning even before eating, due to changes in hormones or a drop in insulin levels. Regular testing is important if you have type 1 diabetes. One option is a continuous blood glucose monitor, which can alert you to highs and lows.

Rollercoaster: Exercise

Physical activity gives a terrific health boost for most people, but people with diabetes should tailor it to their individual needs after medical advice. When you work out hard enough to sweat and raise your heartbeat, your blood sugar may spike upwards, then drop. Intense or endurance type exercise can make your blood sugar drop for at least 24 hours afterwards. Eating a snack before you begin may help. Check your blood sugar before, during and after you exercise.

Rollercoaster: Alcohol

Alcoholic drinks contain plenty of carbs, so at first they will raise your blood sugar. But for as long as 12 hours after drinking, your blood sugar may drop. If you drink, it's best to do so with food, and check your blood sugar. Diabetes UK recommends daily limits of no more than three units a day for men and two for women. One unit is about half a pint of normal strength lager, a small glass of wine or a single measure of spirits.

Rollercoaster: Heat

During the next summer heat wave or on holiday abroad, you'll be safer inside, cooling off, during the hottest time of day. Heat can make your blood sugar more difficult to control. You should test your blood sugar often and drink plenty of water to avoid dehydration. Your medication, glucose meter and test strips can also be affected by high temperatures. Don't leave them in a hot car or in direct sunlight.

Rollercoaster: Female hormones

When a woman's hormones change, so do her blood sugar levels. Keep a monthly record of your blood sugar levels to get a better idea of how your menstrual cycle affects you. Hormone changes during menopause may make it even harder to control your blood sugar levels. Talk to your GP or diabetes nurse about the best ways to manage your blood sugar levels at this stage in life.

Is sugar bad for you?

If you love desserts, don't despair. You don't have to give them up forever, but do limit them. Sugar will raise your blood sugar levels more quickly than other carbohydrates, but diabetes experts now say the total amount of carbohydrates is most important. Just be sure to keep your serving sizes small and take into account the total carbs and calories.

What about the glycaemic index?

Your daily carb total, spread steadily across the day, is one key to good blood sugar control. Some people also monitor the glycaemic index (GI) of foods, a rating of how individual foods raise blood sugar. Beans and wholegrain breads and cereals have a lower GI than white bread or normal pasta. Juice has a higher GI than whole fruit. Want a high GI food? Eating it along with a lower GI food may help control your blood sugar.

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