Hba1 c
- 2. 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%)
- 3. Dr.E.P.Joslin “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
- 4. HbA1c: the blood test with a memory What is HbA1c? Hemoglobin is a protein that makes your red blood cells red-colored. When hemoglobin picks up glucose from your bloodstream, the hemoglobin becomes glycosylated. Glycosylated hemoglobin is HbA1c. The HbA1c test measures the percentage of HbA1c in your blood— a number that corresponds to your average blood glucose for the previous 3 months. HbA1c in your bloodstream.
- 5. Different types of Glycation products are formed from the HbA0depending 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 Glycated Hb - GHb (Previously called glycosylated Hb.)
- 7. Formation of Glycated Haemoglobin HC=O HC=N-βA HC=N+H2-βA HCOH HCOH HCOH HOCH HOCH HOCH β-NH2 + HCOH HCOH HCOH HCOH HCOH HCOH CH2OH CH2OH CH2OH Glucose Schiff Base Amadori Product (Aldimine) (Ketoamine)
- 8. HbA1c: Historical Aspects 1962: Huisman and Dozy Increases in minor fractions of haemoglobin in four diabetic patients treated with tolbutamide. 1968: Rahbar ‘Diabetic haemoglobin component’ found in 49 Iranian diabetic patients. 1968: Rahbar Component the same structure as the previously described HbA1c
- 9. HbA1c: Historical Aspects HbA1c correlated with: Plasma ‘glucose brackets’ Koenig RJ et al. N Engl J Med 1976; 295: 417-420 Daily mean plasma glucose Gonen B et al. Lancet 1977; ii; 734-737 24 hour urinary glucose excretions Gabbay KH et al. J Clin Endocrinol Metab 1977; 44: 859-864 Glucose control over past 6-8 weeks Goldstein D et al. Clin Chem 1986; 32(Suppl): B64-70
- 11. Reference values of HbA1c 1. Less than 6% - Normal 2. 6 to 7% - Good control of DM 3. 7 to 9% - Unsatisfactory control 4. More than 9% - Very poor control Values depend on the method of estimation They vary from lab to lab.
- 12. 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.
- 13. Lowering Hb A1c reduces risk of complications How well it measures ?
- 14. Dr.Sarma@works
- 15. UKPDS: Risk of Macro and Microvascular Complications UKPDS Group. BMJ 2000;321:405-412
- 16. DCCT: Risk of Microvascular Complications DCCT Group. N Engl J Med. 1993; 329: 977-86
- 17. Correlation of MPG - HbA1c Mean Plasma Glucose = (33.3 x HbA1C%) - 86 (Nathan et. al. NEJM, vol. 310, No 6, Feb 9, 1994) HbA1C % 5 7 9 11 Mean BG mg % 80.5 147.1 213.7 280.3
- 18. Dr.Sarma@works
- 19. Dr.Sarma@works
- 20. 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
- 21. 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