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                                 Diabetes  Mellitus

                                                                Andrew Ying-Siu Lee, MD,PhD.

 

       Diabetes mellitus (DM) is due to deficiency of insulin secretion and/or resistance of body's cells to action of

insulin (= insulin resistance) leading to high blood sugar (=hyperglycemia) and disturbances of carbohydrate, fat and

protein metabolism in our body, resulting in diabetic symptoms and complications.

 

       Symptoms of DM include: thirst, polydipsia, polyuria, weight loss,tiredness and malaise, constipation

(due to dehydration), recurrent or refractory infections, visual disturbance, paresthesia (due to peripheral

nerve damage), pruritus, cramp (due to diuresis) etc.

 

       Acute complications of DM include:-

        (1) Hypoglycemia:  Predisposing factors are: excessive dose of insulin or oral hypoglycemic drugs,

                                            inadequate or delayed  food intake, sudden or prolonged exercise, renal and

                                            hepatic failure, diabetic gastroparesis, age, pregnancy, drugs, alcohol, medical

                                            conditions (heart failure, cardiogenic shock, starvation, sepsis, lactic acidosis,

                                            adrenal insufficiency etc.).  Autonomic symptoms include: palpitation, diaphoresis,

                                            anxiety, hunger, irritability, pallor, nausea, angina. Neuroglycopenic symptoms

                                            include: headache, weakness, fatigue, confusion, amnesia, blurred vision, focal

                                            neurologic deficit, seizure, coma etc.

 

        (2) Diabetic ketoacidosis (DKA) and hyperglycemic hyperosmolar syndrome (HHS) :

                                         Predisposing factors are: coexistent medical illness (eg. infection, silent myocardial

                                         infarction, stroke, pancreatitis, mesenteric ischemia), drugs (diuretics, sedative), 

                                         insulin omission and eating disorder.  Symptoms include: nausea, vomiting, thirst,

                                         polyuria, abdominal pain, signs of dehydration, acidotic  respiration, ketones on breath,

                                         hypothermia, deficits in electrolytes (Na, K, Mg, PO4), conscious disturbance.

 

Chronic complications of DM include:

                                  Eye – retinopathy, maculopathy, cataract, squint

                                   Ear – deafness

             Kidney – nephropathy, renal failure, chronic pyelonephritis

              Nerve – peripheral, autonomic neuropathy

               Heart -  coronary artery disease, heart failure

                 Leg – peripheral vascular disease

               Brain – stroke

                Feet – ulcer, infection, gangrene

                Skin – dermopathy, necrobiosis lipoidica

 

 

       American diabetes association diagnostic criteria for diabetes mellitus:-

nDiabetes mellitus (DM)

       - symptoms of DM + casual plasma glucose > 200 mg/dl

       - repeated fasting plasma glucose > 126 mg/dl

       -   repeated plasma glucose > 200 mg/dl at 2 hours after 75 gm oral glucose challenge (not recommended

          for routine use)

nImpaired fasting glucose

         fasting plasma glucose 110-126 mg/dl

nNormal fasting glucose

         fasting plasma glucose < 110 mg/dl

 

American diabetes association classification of diabetes mellitus:-

nType 1 DM (5-10%) :  caused by pancreatic beta cell destruction, often immune mediated à loss of insulin

                                           secretion (absolute insulin deficiency). Common in children and adolescent,

                                           characterized by abrupt onset of severe symptoms, need insulin to substain life,

                                           prone to ketosis.

 

nType 2 DM (90-95%):  caused by genetic and nongenetic factors (eg. age, high calorie intake, overweight,

                                            central obesity, sedentary lifestyle etc) --> insulin resistance and relative (not absolute)

                                            insulin deficiency

 

nOther specific types of DM (1-2%) :  causes include genetic defects affecting beta cell function or insulin

                                                                     action, endocrinopathies, drugs, infection etc.

nGestational DM(3-5%):  caused by insulin resistance and relative insulin deficiency associated with

                                              pregnancy

 

              Type 1 DM need insulin therapy.  If inadequate, oral hypoglycemic drugs such as metformin,

glitazones oracarbose can be added.  Types 2 DM need oral hypoglycemic drugs including : insulin

secretagogues (sulfonyluras, meglitinides,phenylalanine derivatives), metformin, peroxisome

proliferator-activated receptor (PPAR_ modulators (thiazolidinediones), glinides (starlix, novonorm). 

If inadequate, single injection of intermediate-acting insulin at bedtime can be added.

 

               Aside from drug therapy, the mainstays of DM control = weight loss, diet control, exercise, stop

smoking, abstain alcohol and change of lifestyles.  Ideal DM control can prevent (1) ketoacidosis and

hyperosmolar coma, (2) diabetic symptoms and (3) diabetic complications.

 

                                                  Age-adjusted goals of treatment of DM:-

                                    preprandial          postprandial          HbA1c            urinary  glucose  

                                    blood sugar         blood sugar                                    and  ketones

                                        (mg/dl)                    (mg/dl)

 

toddlers/

prescholars                  150-160                      < 250                7.5-8.5%         glycosuria but rare ketonuria

                                         

children/

adolescent/

adults                              140-150                      < 160                6.5-7.4%          intermittent glycosuria, rare ketonuria 

  

elderly with                    150-160                      < 250                7.5-8.5%                                     ,,

neurologic or

cardiovascular

dysfunction

 

                                            HbA1c = glycosylated glucose attached to hemoglobin indicating

                                                             glycemic load during 120 day lifespan of red blood cell