Hb A1c by Dr Sarma by cuiliqing


									                     Paradigm shift in Diabetic care

                 Dr.R.V.S.N. Sarma, M.D., M.Sc.,
                              How true ?
                 Once there was a tiger which boasted
                 that it can run faster than any one.
                 One day he chased a rabbit and failed to
                 catch it.
                 “All right” said the tiger; “of course I
                 failed on my boast.
                 But, remember the rabbit was running
                 for its life and I, for my dinner.”
                  Now, decide who is the rabbit and who
                 is the tiger - among we and our patient !
                 “The greatest burden on doctors will
                 be not the management of diabetes,
                 but the associated macro and micro-
                 vascular complications of it.” ..1926
                 “The goal of therapy in diabetes
                 should be to make serious efforts to
                 keep the blood sugar levels as close
                 normal as possible.” ….. 1929
                         Be serious Doctor
                 1. I am making India the capital of the
                    world shortly !
                 2. Already I have a big… family of 200
                    millions on the globe.
                 3. I am happily troubling 12% urban and
                    8.2% of rural Indians.
                 4. In my name I am sweet but my
                    effects are very hot !
                 5. I am not easily controlled (< 45%)
                 Structure of Hb

                             Different Hbs

                 1.    Fetal Hemoglobin – Hb F
                 2.    Adult Hemoglobin – Hb A
                 3.    Sickle cell disease – Hb S
                 4.    Hemoglobinopathies – Hb C, Hb E

                      Glucose in the blood reacts with the
                      Hemoglobin A to form Glycated Hb.

                      Glycated Hb - GHb
                 Different types of Glycation products
                 are formed from the HbA0 depending
                 on the carbohydrate moiety – namely
                 – HbA1a1 - Fr 1,6 diphos –N-term. valine
                 – HbA1a2 - Gl 6 phos –N-terminal valine
                 – HbA1b - Other CHO – N-term. valine
                 – HbA1c - Glucose –N-terminal valine
                  Normally less than 6% of Hb is HbA1c

                      (Previously called glycosylated Hb.)
                 Reference values of HbA1c
                 1.   Less than 6% - Normal
                 2.   6 to 7.5% - Good control of DM
                 3.   7.6 to 9% - Unsatisfactory control
                 4.   More than 9% - Very poor control
                  Values depend on the method of estimation
                  They vary from lab to lab.
                  Note if all GHb is measured instead of HbA1c

                 Factors affecting HbA1c
                 •   Acute hyperglycemia
                 •   Severe aneamia
                 •   Gestational diabetes
                 •   Life span of the RBC
                 •   Abnormal Hb like S-Hb, Hb C
                 •   Serum opalescence -↑TG
                 •   On the method of estimation
                       Estimation of HbA1c
                 • There are many methods of estimation
                 • HPLC (High Performance Liquid
                   Chromatography) – Gold standard.
                 • Immuno-turbimetric meth. – HbA1cAb
                 • Affinity chromatography
                 • Electrophoretic methods
                 • Method based on chemical reactions.

                 HbA1c is ‘weighted’

                   How well it measures ?
                 Lowering Hb A1c reduces risk of complications

                     Advantages of HbA1c
                 • Index of long-term control over 120
                   days and not a snap shot like PG
                 • Can be done at any time of day
                 • Not influenced by diet, exercise,
                   emotional disturbances on test day
                 • Useful index in clinical trials
                 • Useful if missed drugs / default diet
                 • Useful in DD of stress hyperglycemia
                      Limitations of HbA1c
                 • Cannot be an emergency room test to
                   titrate Insulin or OHA dosage
                 • Cannot register hypoglycemia
                 • More sensitive to sin than repentance –
                   if it is elevated it confirms poor control,
                   if it is boarder line, it cannot assure
                   good control in the recent past.
                 • Not sensitive enough for use in GDM
                 •  Anaemia, Uraemia, Pregnancy
                 Correlation of MPG - HbA1c
                        Mean Plasma Glucose =
                             (33.3 x HbA1C%) - 86
                   (Nathan et. al. NEJM, vol. 310, No 6, Feb 9, 1994)

                   HbA1C %                 Mean BG mg %

                         5                           80.5
                         7                          147.1
                         9                          213.7
                        11                          280.3
                       Glycosylation of hair
                 •   Hair glycosylation using thiobarbituric acid TBA
                 •   Glycosylation of hair is  in diabetes mellitus
                 •   Both insulin dependent , non-insulin dependent
                 •   Glycosylation of hair is proportionate to HbA1c
                 •   Due to the presence of hexosyl lysome in hair
                 •   Long hair sample provides a long term record.
                 •   May have forensic application & in population

                                         BMJ, 1996, vol. 288 pp. 669-670
                  Blood Glucose Monitoring
                     Type          Frequency        Sample

                  Type 2 DM         Monthly       FPG / PPG

                  Type 1 DM         4-6 times      6th hourly
                                     initially    to 4th hourly
                   Stabilized     Twice a week.    3 samples

                  Pregnancy       Once a week.    FPG / PPG

                 Peri-operative     4-6 times      6th hourly
                                      a day       to 4th hourly


                 “Blood Glucose 80 min. after
                  breakfast correlates with MAGE
                  ( Mean Amplitude of Glycaemic
                  Excursions ) throughout the day”

                                           Molnar et. al.

                 •   On intensive insulin therapy
                 •   Diabetes in pregnancy
                 •   IDDM who lack warning symptoms
                     of hypoglycaemia
                 •   Insulin - requiring diabetics
                 •   Diabetics with unusually high/low
                 •   Insulin - resistant diabetics on large
                     insulin doses
                 •   Motivated diabetics for tight control.
                 New era in monitoring control


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