CHARACTERISATION DEVICE FOR INSULIN AND CARBOHYDRATES SENSITIVITY
This invention relates to the fields of diabetes management and diagnoses. It relates in particular to a system able of characterizing patients in terms of insulin sensitivity and ets (equivalent teaspoons sugar) sensitivity by examining their blood glucose response after meals and insulin injections. It also relates to method of operation of such a diabetes characterization system.
In this specification, the term Equivalent Teaspoon Sugar (ets) means an energy unit used for quantifying energy in food and energy usage in exercise.
Furthermore ets can also be used to quantify energy being expended during exercise by relating the energy to the effective energy available in a teaspoon sugar, ets can also be used to express any quantity of energy e.g. the blood glucose energy in the blood or the amount of glycogen energy stored in the liver.
Furthermore, in this specification, the term insulin includes within its scope any blood sugar regulatory substance. Furthermore, in this specification, the term diabetes or diabetic refers to
Type 1 diabetes or Type 1 diabetic respectively unless otherwise stated.
OBJECTS AND ADVANTAGES OF THE INVENTION
In the treatment of diabetes it is important for the medical practitioner to know how the diabetic patient responds to food intake, insulin and exercise. This is necessary to create appropriate meal plans and prescribe insulin regimes for the patient. The primary objective of this invention is to determine the insulin and ets sensitivity of a diabetic patient. It will use the results of a simple test procedure to determine these values. With the characterization test results known to the medical practitioner and patient, more accurate insulin administration will be possible. Insulin and ets sensitivity values will be used by several products able of suggesting insulin dosages or food intake. These products use the sensitivity values in their blood glucose prediction models. These models are then used for accurate insulin prediction. Accurate calculation of values by said invention will allow the diabetic user to use products that can considerably improve the quality and simplicity of their blood glucose control. Said Invention is simple to use and accurately determines ets and insulin sensitivity values of a diabetic patient using a simple blood glucose response test. The main advantage is that the calculation results of the device will be used to configure other products that will considerably improve glycaemic control of Type I diabetics. It will also help the diabetic care provider to establish good diabetic control in a relative short time.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 a shows one side of the ound slider ruler calculating ets sensitivity.
FIG. 1 b shows the other side of the round slide ruler calculating insulin sensitivity.
FIG. 2,3 and 4 shows the main parts of the ets sensitivity calculator forming one side of the round slider ruler.
FIG. 2 shows the blood glucose level scale of the ets sensitivy calculator (bottom layer)
FIG. 3 shows the mask plate covering irrelevant ets sensitivity values (top layer)
FIG. 4 shows the disc with ets sensitivity values (middle layer)
FIG. 5,6 and 7 shows the main parts of the insulin sensitivity calculator forming one side of the round slider ruler.
FIG. 5 shows the blood glucose level scale of the insulin sensitivy calculator (bottom layer).
FIG. 6 shows the mask plate covering irrelevant insulin sensitivity values (top layer).
FIG. 7 shows the disc with insulin sensitivity values (middle layer).
FIG. 8 shows the typical blood glucose response after eating a meal.
FIG. 9 shows the typical blood glucose response after eating injecting short acting insulin.
DETAILED DESCRIPTION The characterisation method used by the invention is based on the ets concepts, ets (Equivalent Teaspoons Sugar) is a quantification method used to quantify the energy content of food and energy expenditure in exercise in terms of ets. This simplifies blood glucose prediction and insulin dosage calculation. ets can generally be used to relate different energy systems present in the human body to each other. In the discussion of this invention it will only be used in the diabetic context involving the different factors that may influence the blood glucose level.
The effect that ets intake has on the increase of blood glucose concentration for the diabetic is approximated by a linear function.
Increase in blood sugar level = EC . ets consumed (1 )
The ets sensitivity value EC can be calculated performing the simple test procedure to determine the individuals blood glucose increase per unit efcconsumed- At high levels of ets intake, the ets sensitivity (EC) decreases. The blood glucose response for ets intake can generally be approximated by two piecewise linear continuous functions shown in FIG. 10. Typical patients eating healthy will normally stay within the first part of the approximation function therefore simplifying blood glucose response prediction with a single linear function.
FIG. 8 shows a typical blood glucose response of a Type I diabetic after eating a meal containing carbohydrates. The meal is ingested after fasting for six hours or longer. The time of the meal is taken as 0 minutes (25). The ets sensitivity test is performed after a six hour fast to eliminate the effects of the previous meal and previous short acting insulin injection. By this time the blood glucose level is stable. The test should not be performed if the patient is stressed or has an illness that can have an effect on the blood glucose levels. The meal that the patient eats during the test should be carefully quantified in ets. This can be done using ets tables published in literature, databases
available on the Internet or other products available. The patient's blood glucose level is measured every 30 minutes after the meal for the next 3 hours using a blood glucose monitor. The maximum value of these blood glucose level measurements will be used to calculate the rise in blood glucose level 23 caused by the meal. The level rise 23 is the difference between the maximum level 22 and the blood glucose level prior to the meal 24. ets sensitivity (EC) can then be calculated.
Increase in bloodsugar level .
EC = (2) ets in meal
ets sensitivity (EC) for higher values of ets intake can also be calculated by eating more ets after the blood sugar stabilized after the meal. Equation (2) can then be used to calculate ets sensitivity (EC) at higher levels of ets intake.
The effect that insulin has on the decrease of blood glucose concentration for the diabetic can also be approximated by a linear function.
Decrease in blood sugar level = /C./units injected (3)
The sensitivity of insulin value IC can be calculated performing the second part of the test procedure. The insulin sensitivity value (IC) gives a good indication of how resistant the patient is to insulin.
FIG. 9 shows a typical blood glucose response of a Type I diabetic after injecting short acting insulin. This response illustrates an initial high blood glucose level being lowered by administering short acting insulin. For the purpose of the test insulin is only injected after the blood glucose level has stabilized after the meal. The time of the short acting insulin injection is taken at 0 minutes (29). The insulin dosage or units to be injected should be sufficient to
lower blood glucose level back to an acceptable value. The patient's blood glucose level is measured right before the injection and every 30 minutes thereafter. The minimum value where the blood glucose level stabilizes is used to calculate the decrease in blood glucose level. This is merely the difference 27 between the stabilized blood glucose level after the meal 26 and the stabilized blood glucose level after the insulin injection 28. The insulin sensitivity can then be calculated. _ Decrease in bloodsugar level resulting from insulin injection . .. number of units insulin injected
To calculate the corrective action needed to control blood glucose level becomes a simple task. The predicted blood sugar level can be calculated using Equation 5.
BSpredicted = BSCυrrent + EC. βtS consumed- I C.I units injected (5)
If we want to control the blood sugar level in a safe range, we specify the SSpredicted value as the desired blood glucose level BSWanted and calculate the
'units needed.
Therefore the s needed can be calculated by manipulating equation 6.
'units needed — ( oSCurrent " β^wanted "*" EC. ΘΪS consumed) ' IC. l)
The effect of exercise can also be introduced in a similar way by quantifying exercise in terms of ets exercised. This will result in a reduction of blood glucose levels per unit exercise performed. Different exercises can be quantified in terms of ets exercised ■ The sensitivity EXC will be determined by the decrease in blood glucose level per unit efsexeraSec/. If exercise is to be considered Equation 7 can be altered.
'units needed — ( S current " unwanted + E . θtS consumed -EχC. etS exercised) / IC. (8)
If /units needed provides a positive value, the value indicates the number of short acting insulin units to inject. If /units needed provides a negative value, this means that the blood glucose level will already be too low without injecting any insulin. This means that some food containing a certain amount of ets should be eaten. To calculate the amount of ets to be eaten to restore normal blood glucose levels equation 9 can be used.
etS to be eaten = (ExC. etS exercised ' "Scurrent + "£ wanted) ' EC (9)
In short if the diabetic knows what the effect of a certain amount of food and exercise will be on his/her bloodsugar, and the diabetic knows what effect one unit of insulin will have on his/her blood glucose level, it becomes an easy task to calculate the required insulin dosage. Therefore it is important to calculate the ets and insulin sensitivity values accurately using the device.