INTRODUCTION
Imperfect dieting is a major cause of the progression (i.e. inevitably getting worse) of diabetes.  Due to insufficient understanding of diabetes, patients when diagnosed do not receive all the information necessary to reliably control their diabetes by diet and exercise alone.  This shortcoming accelerates progression of their diabetes into both medication – e.g. one tablet, tablets, then insulin, with a variety of possible side-effects – and also grisly diabetic complications.  These diabetic complications are mainly: coronary heart disease (from which about 80% of diabetics die prematurely in developed countries), stroke, blindness, kidney failure, lower leg amputation, impotence, and other body-wide nerve damage.  Accelerated mental decline and Alzheimer's disease also occur with poorly controlled diabetes.  Ask any diabetic, with any of these complications, if you doubt the importance of staying free from them.  Three people die every hour from diabetes-related complications in the UK, according to Diabetes UK.

The DiabeticOptiCarbDiet (henceforth DOCD) is probably the first comprehensive lifestyle change package that can reliably delay both diabetic complications and blood glucose (henceforth BG) control medication over the long term (i.e. 11 years, and still counting).  So DOCD is intended for Type 2 diabetics and pre-diabetics trying to control their BG by healthy diet and exercise alone.  This ability to delay diabetic complications, ideally up to the end of the diabetic's natural life or until a cure for Type 2 is available (if sooner), is the most important requirement from any diabetic diet.

DOCD was created by a Type 2 diabetic (Dr Roger Grant – a scientific PhD, with a GP doctor wife; more background in footnote), initially just for his self-preservation and continued enjoyment of healthy food.  Aware of both the uncertainties surrounding the effects of medicinal chemicals on the body and their benefits, he preferred to control his diabetes by healthy diet and exercise alone for as long as possible.  He is now in his 12th year of freedom from both complications and medication, and eating enjoyably.  This in spite of DOCD indicating that his pancreas produces little natural insulin, due to significant beta-cell exhaustion.  DOCD has kept his 6-monthly DCCT-aligned HbA1c* test values in the narrow range of 6.2-7.3% (last two values both 6.2%) since early 2001 (when the test method was revised), after an equivalent value at diagnosis of 8.6% in 1988.  In the new lingo, these values translate into 44-56 mmol/mmol, and 70 mmol/mmol at diagnosis.  After the initial highly detailed 5-year case study of himself, Roger piloted the findings among other diabetics for 3 years to provide wider perspective on their applicability.  He then rewrote DOCD, so as to make it easier to follow and less time-consuming for healthcare professionals, but without reducing its effectiveness.

* HbA1c is the percentage of glucose attached to the blood's hemoglobin, and so an indicator of BG level – both averaged over the previous 2 to 3 months.

HOW DOCD OVERCOMES THE SHORTCOMINGS OF OTHER DIABETIC DIETS
Early in the research, Roger recognized some fundamental shortcomings in existing advice on BG control by diet and exercise alone.  These shortcomings were of a quantitative nature, and were undermining the benefits of the better understood (and simpler) qualitative aspects such as 'healthy’ fats (e.g. monounsaturateds and omega-3s) and 'unhealthy' fats (e.g. trans), etc.  It is a basic principle of control, that to control something adequately it has to be measured suitably.  So the quantitative aspects are an essential part of successful BG control.  These quantitative shortcomings were mainly:

1. Insufficiently precise ways of determining the ‘safe’ (i.e. optimum) weight of each healthy carbohydrate-containing food for each snack or meal.  This in spite of the amount of carbohydrate (henceforth carb) eaten being recognized as the strongest single influence on postprandial (i.e. after eating) BG magnitude.  Each time a person eats carb, their BG level rises to a postprandial peak, and then decreases with the assistance of the insulin produced by their pancreas.   (See diagram below).  In non-diabetics, these BG peaks can go up to about 10.0 mmol/L** (180 mg/dL in US units).  In diabetics, the high BG damage leading to complications is seen as resulting during time spent above this 10.0 mmol/L level.  So DOCD is aimed at keeping BG level below the levels at which the artery damage causing complications occurs – by limiting the postprandial BG peak from going above 9.0 mmol/L (162 mg/dL) normally, and very seldom going above 10.0 mmol/L.  By way of perspective, when Type 2 diabetes is diagnosed, macrovascular (i.e. large artery) damage, which leads to coronary heart disease and stroke, has usually been present for some years. If BG value is allowed to spend time above 10.0 mmol/L, microvascular (i.e. small artery) damage follows, and this leads to the other complications listed in the first paragraph. High BG levels also aggravate existing macrovascular damage.
   

   ** All BG values are for glucose meters reporting their results as capillary whole blood – as distinct from those tuned to report as venous blood plasma, which give approximately 12% higher values. Look in the instructions to see which your meter does.
   

   Official past guidelines for determining suitable food weights for snacks and meals have been Exchanges, Carb Counting, the Food Pyramid, MyPyramid, and 40-60% of daily energy (i.e. calorie) intake being (mainly starchy) carb. (40% is a Joslin Center value).  None were sufficiently helpful for diet alone control. When the DOCD research began, there was institutional advice to keep postprandial BG peak below 10.0 mmol/L (180 mg/dL) two hours after starting to eat.  See how this criterion works for the diagram.  It shows the postprandial curves for a Type 2 diabetic and a non-diabetic eating 70 dry g of cooked porridge (no sugar!) under the same conditions with the preprandial starting point being moved to 6.0 mmol/L in both cases.  (The non-diabetic’s was actually 5.0 mmol/L).  The diabetic’s BG comfortably met the advice of being below 10 mmol/L two hours after starting.  Yet it peaked at 12.2 mmol/L (220 mg/dL) and spent 65 min above 10.0 mmol/L.  In late 2008, the UK’s National Institute for Health and Clinical Excellence changed its recommendation to keeping below 8.5 mmol/L two hours after eating, but that would not have improved this situation much.  Evidently these criteria did not serve their intended purpose.  The problem confounding such a criterion is the dependence of the shape of each BG/time curve on the individual person, other foods present and their amounts, their Glycemic Index (henceforth GI), previous food eaten, etc.  It will work better for some medications, but not for diet alone control where typically there is little, or no, first release of pancreatic insulin and a weak second release.
   

   DOCD follows the 40-60% carb advice mentioned above, but not the “(mainly starchy) carb” aspect.  This latter advice led to the creation of alternative diets – due to starchy foods having high GIs and therefore pushing up BG.  Among these are low-carb diets, which approach the problem by intentionally selecting very low carb weights (much lower than DOCD’s, which is not low-carb).  However, more calories then have to come from fats and proteins, and the long term health effect of this, together with fewer and less of the nutrients gained from eating carb, is queried. DOCD, from its beginning included some aspects of other diets, such as the healthy food in the Mediterranean Diet and the ‘gentle’ foods of the Low GI Diet.  However DOCD followers can also eat ‘non-Mediterranean’ healthy foods, and medium and high GI foods, and treats – but all in the correct amount.
   

   To identify the postprandial peak values, the DOCD research included over 100 variously structured eating experiments, using finger BG testing at 10 min intervals (as in the diagram above).  The main finding from analyzing the data was a method for determining the maximum (i.e. ‘safe’) weight of any carb-containing food(s) a diabetic could eat without their postprandial BG peak going above 9.0 mmol/L (162 mg/dL) normally, and very seldom going above 10.0 mmol/L.  Lower upper limits may be possible for some people.  Also, from piloting the findings among other diabetics, that each diabetic had their own league of such food weights, according to their diabetic severity, etc.  (As is frequently said: “Everyone is different” and "One size doesn't fit all").  A quick and simple short-cut was developed to enable DOCD users to determine their personal such weights.  Please note that although these food weights are the maximum food weights that can be eaten ‘safely’ (i.e. optimum carb) from a BG viewpoint, lesser quantities may be eaten if desired.  This may be necessary when people are losing weight and is, in any case, kinder to the pancreas.
   

2. Too much noise.  The word “noise” given to radio interference, is also used for unwanted irregular influences that interfere with drawing conclusions from experiments.   (You have probably encountered them in your own BG testing).  Commonly, a vicious circle (cycle) is prevailing when a person first starts following DOCD.  As the pancreas is treated more kindly, by lowering postprandial peaks and other DOCD measures, so the vicious circle gradually changes into a virtuous circle, that is more predictable and seems almost cooperative!   (There are good medical explanations for this slow change).  This does not mean that your diabetes has been cured.  It can revert back towards the vicious circle, for example on holiday, due to greater eating and drinking and the different choice of foods, but DOCD has approaches for returning to the virtuous circle.  Similarly celebratory meals and ‘treats’ can be returned to virtuous conditions, providing they are not too frequent.
   

3. No ‘real time’ feedback. In many industrial processes, there are instruments providing continuous measurements of important end-product properties.  For example, measuring thickness, so that the end-product is not too thick, and therefore wasteful of material, or too thin, and therefore too weak.  Process changes are then made automatically so as to correct the situation.  This is called “real time” feedback, because the information is fed back sufficiently rapidly for it to be used to correct the process.  Compare this with making a change to your dieting, and then having to wait up to 3 months, or maybe 6 months, for the result of your next HbA1c and other blood test results.  Even then, since HbA1c is an average of BG values over the previous 3 months, it can tell you nothing about how you dieted for any particular snack or meal.  By contrast, because DOCD eliminates most of the “noise” that upsets the interpretation of readings (Item 2 above), it does provide a simple method of real time feedback that enables one’s dieting techniques to be progressively improved.
   

4. Meaningless BG testing.  There is an on-going debate in the UK National Health Service as to whether those controlling by diet alone should be given any test strips (or equivalent) for finger testing, because using them has generally not shown BG improvements.  The likely explanation, for this lack of success, is patients having been told either to keep below 10.0 or 8.5 mmol/L after 2 hr (which can result as in the diagram above), or to do other spot tests that are not meaningful.  By contrast, DOCD’s use of peak postprandial values to determine the maximum weight of foods that can be eaten without BG going up to dangerous levels, effectively does away with postprandial testing.   DOCD also looks after preprandial levels, so that once the diabetic has settled down inside DOCD (the time depends mainly on how hard they work at it), finger test monitoring can be reduced to once per week.  Occasional ‘spot’ tests and experimentation are additional. That way patients get the information they need and the NHS economizes on strips.