The short-term effectiveness of low-carbohydrate diets for weight reduction is well established [2–6]. Weight reduction is primarily caused by decreased caloric intake [2–6] although decreased energy efficiency has also been found . A high-starch, high-carbohydrate diet excessively stimulates appetite and disturbs energy balance in patients with the metabolic syndrome and type 2 diabetes . A reduction of carbohydrates normalises the balance, reduces insulin concentrations and favours utilization of stored fat as fuel as well as significantly reducing insulin resistance . Weight loss in overweight persons is improved by a higher proportion of protein, presumably due to protein's effect on satiety and/or metabolic efficiency [7, 9–11]. A reduction in carbohydrates for patients with type 2 diabetes effectively reduces both fasting and postprandial glucose as well as HbA1c. These effects can be independent of weight loss [8, 12, 13].
Critics of the low-carbohydrate dietary approach usually point to the lack of long-term studies. The change of diet described here in combination with the usual diabetes care has produced long periods of increased well-being in these patients. It is significant that 44 % of the patients have had a stable weight or have reduced it further and all but one had a lower weight at 22 months than at the beginning of the study. Twenty-five % of the patients had previously been dieting continuously and another 50 % had tried to lose weight many times. The reasons they gave for not continuing their previous weight loss programs were 1) constant hunger, and 2) no effect on bodyweight despite strict calorie counting and fat reduction. The lack of hunger and cravings with the low-carbohydrate diet may be an important reason for their present success.
Regular self measurement of blood glucose has probably made it possible for these patients to succeed. Self determination of blood glucose provides a feed-back mechanism and may be another reason that 44 % of the patients succeeded in maintaining their weight.
For most insulin-treated patients, we found that it was necessary to be one step ahead in lowering the insulin doses, that is, if weight loss stopped, and the patient was adhering to the diet (as judged by blood glucose values), even a minor reduction of the insulin dose normally resulted in continued weight loss and presumably continued motivation. This close supervision may be another reason for the patients' initial success.
Improved HbA1c is associated with a reduced incidence of microvascular and macrovascular complications [14–16]. The original low carbohydrate group had maintained a significantly lower mean HbA1c for almost 2 years and a reduced vascular morbidity might therefore be expected in this group. Similarly, intentional weight loss in type 2 diabetes patients is associated with a reduced mortality of 30–40 % . For the average patient each 1 kg weight loss is associated with 3–4 months prolonged survival  making it likely that the patients described here have achieved a survival benefit.
At some point following a reduction of bodyweight and insulin resistance, a decrease of cardiovascular risk would be expected [19, 20]. We have examined the medical charts for both the original high-carbohydrate group and the low-carbohydrate group from 3 months after the initiation of the diet therapy – when an effect might be detected – and forward for episodes of cardiovascular disease. Three episodes of cardiovascular disease have occurred among the 5 patients that never changed diet. The 16 patients in the low-carbohydrate diet group (19 months observation time) and the 7 from the high-carbohydrate diet group that changed diet (10 months observation time) – totalling 23 patients – have been free of cardiovascular disease during the follow-up period (p < 0.03. Fischer Exact).
Several recent reviews have made the case for reducing the carbohydrate load in type 2 diabetes [21–23] or metabolic syndrome  and the low-carbohydrate diet presented here is clearly effective in many obese people with type 2 diabetes. Because of its effectiveness it should be used with close clinical supervision in patients on insulin or oral hypoglycaemic agents.
In summary, a reduced carbohydrate diet is an effective tool in the management in motivated obese patients with type 2 diabetes. The effect is generally retained after almost 2 years. There has been no evidence of a negative cardiovascular effect among the 16 subjects.