Background: Low-carbohydrate diets, due to their potent antihyperglycemic effect, are an intuitively attractive approach to the management of obese patients with type 2 diabetes. We previously reported that a 20% carbohydrate diet was significantly superior to a 55-60% carbohydrate diet with regard to bodyweight and glycemic control in 2 groups of obese diabetes patients observed closely over 6 months (intervention group, n = 16; controls, n = 15) and we reported maintenance of these gains after 22 months. The present study documents the degree to which these changes were preserved in the low-carbohydrate group after 44 months observation time, without close follow-up. In addition, we assessed the performance of the two thirds of control patients from the high-carbohydrate diet group that had changed to a low-carbohydrate diet after the initial 6 month observation period. We report cardiovascular outcome for the low-carbohydrate group as well as the control patients who did not change to a low-carbohydrate diet.
Method: Retrospective follow-up of previously studied subjects on a low carbohydrate diet.
Results: The mean bodyweight at the start of the initial study was 100.6 +/- 14.7 kg. At six months it was 89.2 +/- 14.3 kg. From 6 to 22 months, mean bodyweight had increased by 2.7 +/- 4.2 kg to an average of 92.0 +/- 14.0 kg. At 44 months average weight has increased from baseline g to 93.1 +/- 14.5 kg. Of the sixteen patients, five have retained or reduced bodyweight since the 22 month point and all but one have lower weight at 44 months than at start. The initial mean HbA1c was 8.0 +/- 1.5%. After 6, 12 and 22 months, HbA1c was 6.1 +/- 1.0%, 7.0 +/- 1.3% and 6.9 +/- 1.1% respectively. After 44 months mean HbA1c is 6.8 +/- 1.3%.Of the 23 patients who have used a low-carbohydrate diet and for whom we have long-term data, two have suffered a cardiovascular event while four of the six controls who never changed diet have suffered several cardiovascular events.
Conclusion: Advice to obese patients with type 2 diabetes to follow a 20% carbohydrate diet with some caloric restriction has lasting effects on bodyweight and glycemic control.