If type 2 diabetes were an infectious disease, passed from one person to another, public health officials would say we’re in the midst of an epidemic. This difficult disease is striking an ever-growing number of adults, and with the rising rates of childhood obesity, it has become more common in youth, especially among certain ethnic groups.

The good news is that prediabetes and type 2 diabetes are largely preventable. About 9 in 10 cases in the U.S. can be avoided by making lifestyle changes. These same changes can also lower the chances of developing heart disease and some cancers. The key to prevention can be boiled down to five words: Stay lean and stay active.

What if I already have diabetes?

Guidelines for preventing or lowering your risk of developing type 2 diabetes are also appropriate if you currently have a diabetes diagnosis. Achieving a healthy weight, eating a balanced carbohydrate-controlled diet, and getting regular exercise all help to improve blood glucose control. If you are taking insulin medication, you may need more or less carbohydrate at a meal or snack to ensure a healthy blood glucose range. There may also be special dietary needs for exercise, such as bringing a snack so that your blood glucose does not drop too low.

Control your weight

Excess weight is the single most important cause of type 2 diabetes. Being overweight increases the chances of developing type 2 diabetes seven-fold. Being obese makes you 20 to 40 times more likely to develop diabetes than someone with a healthy weight.

Losing weight can help if your weight is above the healthy-weight range. Losing 7-10% of your current weight can cut your chances of developing type 2 diabetes in half.

Get moving—and turn off the television

Inactivity promotes type 2 diabetes. Working your muscles more often and making them work harder improves their ability to use insulin and absorb glucose. This puts less stress on your insulin-making cells. So trade some of your sit-time for fit-time.

Long bouts of hot, sweaty exercise aren’t necessary to reap this benefit. Studies suggest that walking briskly for a half hour every day reduces the risk of developing type 2 diabetes by 30%. More recently, The Black Women’s Health Study reported similar diabetes-prevention benefits for brisk walking of more than 5 hours per week. This amount of exercise has a variety of other benefits as well. And even greater cardiovascular and other advantages can be attained by more, and more intense, exercise.

Television-watching appears to be an especially-detrimental form of inactivity: Every two hours you spend watching TV instead of pursuing something more active increases the chances of developing diabetes by 20%; it also increases the risk of heart disease (15%) and early death (13%). The more television people watch, the more likely they are to be overweight or obese, and this seems to explain part of the TV viewing-diabetes link. The unhealthy diet patterns associated with TV watching may also explain some of this relationship.

Tune Up Your Diet

Four dietary changes can have a big impact on the risk of type 2 diabetes.

1. Choose whole grains and whole grain products over refined grains and other highly processed carbohydrates.
2. Skip the sugary drinks, and choose water, coffee, or tea instead.
3. Choose healthy fats.
4. Limit red meat and avoid processed meat; choose nuts, beans, whole grains, poultry, or fish instead.

Don’t smoke

Add type 2 diabetes to the long list of health problems linked with smoking. Smokers are roughly 50% more likely to develop diabetes than nonsmokers, and heavy smokers have an even higher risk.

Light to moderate alcohol consumption

Evidence has consistently linked moderate alcohol consumption with reduced risk of heart disease. The same may be true for type 2 diabetes. Moderate amounts of alcohol—up to a drink a day for women, up to two drinks a day for men—increases the efficiency of insulin at getting glucose inside cells. And some studies indicate that moderate alcohol consumption decreases the risk of type 2 diabetes. [1, 34-39], but excess alcohol intake actually increases the risk. If you already drink alcohol, the key is to keep your consumption in the moderate range, as higher amounts of alcohol could increase diabetes risk.