Type 2 Diabetes: Etiology and Reversibility

Implication for Management of Type 2 Diabetes

The extent of weight loss required to reverse type 2 diabetes is much greater than conventionally advised. A clear distinction must be made between weight loss that improves glucose control but leaves blood glucose levels abnormal and weight loss of sufficient degree to normalize pancreatic function. The Belfast diet study provides an example of moderate weight loss leading to reasonably controlled, yet persistent diabetes. This study showed that a mean weight loss of 11 kg decreased fasting blood glucose levels from 10.4 to 7.0 mmol/L but that this abnormal level presaged the all-too-familiar deterioration of control.^[87]

Data from the Swedish randomized study of gastric banding showed that a loss of 20% body weight was associated with long-term remission in 73% of a bariatric surgery group, with weight change itself being the principal determinant of glucose control.^[13] Dietary weight loss of 15 kg allowed for reversal of diabetes in a small group of individuals recently receiving a diagnosis.^[21] In individuals strongly motivated to regain normal health, substantial weight loss is entirely possible by decreasing food consumption.^[88] This information should be made available to all people with type 2 diabetes, even though with present methods of changing eating habits, it is unlikely that weight loss can be achieved in those not strongly motivated to escape from diabetes. Some genetic predictors, especially the Ala12 allele at PPARG, of successful long-term weight loss have been identified,^[89] and use of such markers could guide future therapy. It must be noted that involuntary food shortage, such as a result of war, results in a sharp fall in type 2 diabetes prevalence.^[90,91]

The role of physical activity must be considered. Increased levels of daily activity bring about decreases in liver fat stores,^[43] and a single bout of exercise substantially decreases both de novo lipogenesis^[39] and plasma VLDL.^[92] Several studies demonstrated that calorie control combined with exercise is much more successful than calorie restriction alone.^[93] However, exercise programs alone produce no weight loss for overweight middle-aged people.^[94] The necessary initial major loss of body weight demands a substantial reduction in energy intake. After weight loss, steady weight is most effectively achieved by a combination of dietary restriction and physical activity. Both aerobic and resistance exercise are effective.^[95] The critical factor is sustainability.

Formal recommendations on how to reverse type 2 diabetes in clinical practice must await further studies. In the meantime, it will be helpful for all individuals with newly diagnosed type 2 diabetes to know that they have a metabolic syndrome that is reversible. They should know that if it is not reversed, the consequences for future health and cost of life insurance are dire, although these serious adverse effects must be balanced against the difficulties and privations associated with a substantial and sustained change in eating patterns. For many people, this may prove to be too high a price to pay, but for those who are strongly motivated to escape from type 2 diabetes, the new understanding gives clear direction. Physicians need to accept that long-term weight loss is achievable for a worthwhile proportion of patients.^[96] In the United States, diabetes costs $174 billion annually,^[97] and in the United Kingdom, it accounts for 10% of National Health Service expenditure. Even if only a small proportion of patients with type 2 diabetes return to normal glucose control, the savings in disease burden and economic cost will be enormous.

Diabetes Care. 2013;36(4):1047-1055. © 2013 American Diabetes Association, Inc.