Tuesday, December 29, 2015

Diabetes Epidemic & You: Part 1

I recently read ‘Diabetes Epidemic & You’ by Dr. Joseph Kraft, a pathologist whose clinic conducted 14,384 oral glucose tolerance tests with insulin assays.  This book is primarily about the results from those oral glucose tolerance tests and the diabetes epidemic in general.  I found the book quite interesting and would be ideal for clinicians or people who are just interested in the topic

* I’ve kept the units for glucose in mg/dl.  To convert to mmol/l simply divide by 18

The Importance of the Oral Glucose Tolerance Test

One of the early points in the book is that fasting blood glucose is not always a reliable diagnostic measure of impaired glucose tolerance (IGT; 2 hour glucose = 140-199 mg/dl) or type 2 diabetes (T2D; 2 hour glucose ≥ 200 mg/dl).  The first table looks at the percentage of people who have a fasting glucose below certain points within each category of glucose tolerance.  This table highlights that 60% with impaired glucose tolerance and 20% with type 2 diabetes have normal fasting glucose.  These particular people would often have their problem of impaired glucose tolerance or type 2 diabetes go unnoticed as most doctors initially rely solely on fasting glucose

Fasting Blood Glucose (mg/dl)
NGT (%)
(N=9598)
IGT (%)
(N=2775)
T2D (%)
(N=2011)
< 110
99
84
40
< 100
93
60
20
< 90
71
32
13
< 80
32
12
4
< 70
9
9
2
< 60
2
2
< 1

The following table is based on data from the previous and lists the percentage of people by categories of both fasting glucose (FBG) and glucose tolerance.  Just keep in mind that this is unlikely to be a representative sample given the skew in the sample towards women (73.4%) and 21-60 year olds

FBG (mg/dl)
NGT (%)
IGT (%)
T2D (%)
TOTAL (%)
> 110
0.7
3.1
8.4
12.1
100-110
4.0
4.6
2.8
11.4
90-100
14.7
5.4
1.0
21.1
80-90
26.0
3.9
1.3
31.1
70-80
15.3
0.6
0.3
16.2
< 70
6.0
1.7
0.3
8.0
TOTAL
66.7
19.3
14.0


And finally, using the same results, this table lists the percentage of people who have normal, impaired and diabetic glucose tolerance for each category of fasting glucose.  For example, if your fasting glucose is between 90-100 mg/dl you have a 25.6% of having impaired glucose tolerance

FBG (mg/dl)
NGT (%)
IGT (%)
T2D (%)
> 110
5.5
25.4
69.1
100-110
35.0
40.5
24.5
90-100
69.7
25.6
4.6
80-90
83.6
12.4
4.0
70-80
94.7
3.6
1.7
< 70
74.9
21.6
3.5

Fasting Insulin

Dr. Kraft makes a similar point for fasting insulin – that it’s not a great indicator of glucose tolerance.  At least fasting glucose was quite effective at identifying individuals with T2D, fasting insulin appears to be quite a bit worse.  The first table is the percentage of people with fasting insulin at various for each category of glucose tolerance

Insulin (mU/ml)
NGT (%)
IGT (%)
T2D (%)
0-10
53
43
33
11-15
23
19
19
16-20
11
14
14
20-30
8
14
18
> 30
5
10
16

The second table is based on data from the previous and lists the percentage of people by categories of both fasting insulin and glucose tolerance (again, may not be representative)

Insulin (mU/ml)
NGT (%)
IGT (%)
T2D (%)
TOTAL (%)
0-10
35.4
8.3
4.6
48.3
11-15
15.3
3.7
2.7
21.7
16-20
7.3
2.7
2.0
12.0
20-30
5.3
2.7
2.5
10.6
> 30
3.3
1.9
2.2
7.5
TOTAL
66.7
19.3
14.0


And the final table lists the percentage of people who have normal, impaired and diabetic glucose tolerance for each category of fasting insulin 

Insulin (mU/ml)
NGT (%)
IGT (%)
T2D (%)
0-10
73.3
17.2
9.6
11-15
70.8
16.9
12.3
16-20
61.2
22.5
16.3
20-30
50.6
25.6
23.8
> 30
44.5
25.7
29.8

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