Look AHEAD at one year: lifestyle support in type 2 diabetes

Why this study matters

Many Canadians live with type 2 diabetes and a higher body weight. A common question is whether a structured program of diet and physical activity can lead to real weight loss and better blood sugar control. Look AHEAD (Action for Health in Diabetes) was a large trial built to answer a bigger question: does intentional weight loss reduce heart attacks and strokes in people with type 2 diabetes? This paper reports what happened in the first year. It looks at weight and risk factors, not heart events.

Who was in the study

The trial enrolled 5,145 adults with type 2 diabetes. They were aged 45 to 74 years. All had a body mass index (BMI) above 25. BMI is a number that compares weight with height, calculated as weight in kilograms divided by height in metres squared. People taking insulin needed a BMI above 27. The study ran at many centres. The published summary does not say which countries took part. This report covers the first year of the trial.

What the researchers did

This was a randomized controlled trial. Randomized means a computer, not a doctor or the participant, decided which group each person joined. This makes the two groups alike at the start, so differences later can be traced to the program.

One group received an intensive lifestyle intervention. It included group and individual meetings aimed at losing weight and keeping it off. People were asked to eat fewer calories and to be more physically active.

The other group received diabetes support and education. This was the comparison condition. The summary we reviewed does not describe it in detail. No weight-loss medicine was part of either program.

What they found

The main result in this report is the change in body weight at one year. The intensive lifestyle group lost an average of 8.6% of their starting weight. The diabetes support and education group lost 0.7% (R32-C89). The paper reports this difference as statistically significant, meaning it was unlikely to be due to chance. The summary does not give a confidence interval for the difference. A confidence interval is the range of values that the true effect would likely fall within.

Other results at one year:

HbA1c is a blood test that reflects average blood sugar over about the past three months.

The lifestyle group also had larger improvements in blood pressure, triglycerides (a type of blood fat), HDL cholesterol (often called "good" cholesterol), and a urine test for early kidney strain. A larger share of lifestyle-group participants were able to reduce their diabetes, blood pressure and cholesterol medicines during the year. The summary reports these as significant differences but does not give the numbers.

Side effects and people who stopped

The published summary we reviewed does not report side effects. It also does not report how many people in each group left the study during the first year.

What this study does not tell you

• Better risk factors do not prove fewer heart attacks or strokes. That was the trial's main goal, and this report does not answer it.
• One year is a short time for weight change. The four-year and eight-year reports show how much was kept off.
• The program was intensive, with frequent meetings. Results may differ with less support.
• Only people aged 45 to 74 with type 2 diabetes took part. The findings may not apply to younger adults or to people without diabetes.
• The summary we reviewed does not state who funded the study.
• Our summary is based on the abstract and extracted data, not the full paper.

What it means in Canada

This study shows what a structured, high-contact lifestyle program achieved in the first year for adults with type 2 diabetes. It does not involve any medicine. Readers curious about how lifestyle programs and medicines are used together can read about semaglutide in Canada and tirzepatide in Canada. For questions about what provincial plans pay for, see public drug coverage by province. To find programs and services, see compare services.

Related reading

Other studies in this library that bear on the same question.

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