Meal planning using food exchange lists is problematic for many elderly type 2 diabetic subjects because the system is too complicated and too rigid regarding the daily meals. In addition, exchange lists are calorically imprecise. 12 non-insulin-dependent diabetic subjects agreed to participate in the present study (6 male, 6 female; age 40-82 years, weight 80 +/- 6 kg; HbA1c 7.3 +/- 0.3%); they received sequentially in randomized order either a diet using exchange lists, or a diet defined by total amount of allowed daily calories (`calorie diet`), both containing approx. 25 calories/kg ideal body weight/day, each for 8 weeks. The `exchange lists` mainly contained foods which were defined according to their content in carbohydrates (including bread exchanges, fruit exchanges, milk exchanges, vegetable exchanges). With the `calorie diet` the patients were relatively free during the day, the only rule being that they were allowed to consume a certain amount of calories per day, using a `calorie ruler`. The results demonstrated that body weight decreased similarly during both diet periods (2.0 +/- 0.8 kg during the exchange list diet; 2.5 +/- 0.9 kg during the `calorie diet`). Fasting blood glucose concentration decreased during the `calorie diet` by 7% (p less than 0.05; fasting blood glucose at the end of the `calorie diet` was lower than after the exchange list diet (p less than 0.016). Serum lipoproteins were similar after both diet periods. 10/12 patients preferred the `calorie diet` because of its simplicity and flexibility. It allowed consumption of instant food which was calorically defined but difficult to convert into the exchange system.(ABSTRACT TRUNCATED AT 250 WORDS)