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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