This is a disease process characterized by either a relative (type II) or absolute deficiency (type I) of endogenous insulin. This disease manifests as hyperglycemia with all of the related symptoms of end organ damage (retinopathy, nephropathy, neuropathy) and microvascular/macrovascular complications. Common presenting symptoms include headache, nocturia, weight loss, glove and stocking neuropathy, and visual changes. A complete discussion of this common disease is beyond the scope of this program.
Diagnosis of type I DM is often simplified when patients present with diabetic ketoacidosis (DKA) but may also be established in the presence of hyperglycemia in young patients who respond only to insulin therapy. Type II DM often occurs for years before the diagnosis is established during routine blood work. Guidelines for the diagnosis of DM include:
1) fasting serum glucose values greater than 126 mg/dL on two separate occasions or
2) glucose tolerance test (GTT) that shows a 2-hour glucose value greater than 200 mg/dL and at least one other value greater than 200 mg/dL during the test (two values greater than 200 mg/dL are needed to confirm the diagnosis and the test should be performed twice) or
3) a random plasma glucose concentration greater than 200 mg/dL on two occasions plus the presence of the classic symptoms of diabetes (polydipsia, polyuria, polyphagia, and weight loss)
4) a random hemoglobin A1C greater than 6.5
The diagnosis of impaired glucose tolerance (IGT) is made if during the GTT there is a 2-hour value between 140 and 199 mg/dL or the hemoglobin A1C is greater than 6 but less than 6.5. Patients with IGTand gestational diabetes are thought to have a propensity to progress to DM II. Significant weight loss and a proper diet are the most effective measures to prevent progression towards diabetes mellitus. Consider acromegaly or Cushing's syndrome in patients with appropriate associated symptoms.
Treatment of type I diabetes mellitus entails exogenous insulin and proper dietary restrictions. Initial dosages are calculated at 0.6 U/kg/day and are titrated up or down to establish euglycemia. Various insulin formulas exist but two commonly used regimens are a twice daily dosage of 70/30 or 75/25 insulins with 2/3 of the daily dosage before breakfast and the remaining 1/3 before the dinner meal. The insulin dosages are then titrated upwards or downwards to maintain an Hgb A1C of less than 7. Basal insulin regimens are started with a once daily dosage of basal insulin started before bed along with a rapid acting insulin before each meal. The AM and PM fasting sugars are followed and the basal insulin dose is increased to lower the fasting values to approximately 100 mg/dL. Next, the preprandial rapid acting insulin is titrated to lower one hour postprandial sugars to less than 180 mg/dL. An insulin pump is also another potential therapeutic option. Initial treatment of type II diabetes mellitus entails following American Diabetes Association dietary restrictions and weight loss. If this does not accomplish a target A1C of 7 or less, then oral therapy with either a sulfonylurea, biguanide, alpha-glucosidase inhibitor, thiazolidinedione, or dipeptyl peptidase IV inhibitor therapy may be started, which if ineffective should be followed by initiating combination therapy with these medications plus injectable insulin or incretin mimetic therapy. Insulin therapy may be initiated as described above for type I diabetes.
All diabetics should be started on diet therapy aimed at approaching the ideal body weight (IBW). IBW may be calculated in the following manner:
Allow 100 lbs for the first 5 feet in height, then allow 5 lbs for each inch over 5 feet. Ten percent of the calculated IBW may be added or subtracted for persons with large or small builds, respectively.
Allow 106 lbs for the first 5 feet in height then allow 6 lbs for each inch over 5 feet. Ten percent of the calculated IBW may be added or subtracted for persons with large or small builds, respectively.
Calculation of the daily caloric requirement may then be done using the IBW. This is done by multiplying the IBW by 13, 15, or 20 calories/day for persons with sedentary, normal, or strenuous lifestyles, respectively. Once the daily caloric requirement is determined as above, 500 calories per day are added or subtracted to initiate weight gain or loss when needed.
Insulin requirements may increase when diabetics become ill. In diabetic patients who suffer from an infection, euglycemia should be aggressively pursued to promote wound healing. Patients who are insulin-dependent should be instructed to wear an identification alert bracelet in the event of an emergency.
Long-term care for diabetics entails monitoring for retinopathy, nephropathy (annual urinary microalbumin determination), infections, neuropathy, and peripheral vascular disease. Type I diabetics should have a baseline ophthalmologic exam 5 years after the onset of disease and annually thereafter. Type II diabetics should undergo baseline ophthalmologic examination at the time of diagnosis and then on an annual schedule. All diabetics should undergo annual urinalysis. If this is positive for proteinuria, then ACE inhibitor or ARB therapy should be initiated as tolerated. If urinalysis is negative for proteinuria, then patients should undergo testing for microalbuminuria. Microalbuminuria should be treated the same as proteinuria. The presence of either microalbuminuria or proteinuria is a marker for progression toward nephropathy and cardiovascular events. Diabetes mellitus is a risk factor for coronary artery and peripheral vascular disease. Therefore, patients should be monitored for hypercholesterolemia and treated accordingly. HMG-CoA reductase inhibitors are often used for the treatment of diabetics with hyperlipidemia but combination therapy with multiple agents may be required. Antiplatelet therapy should be considered in all diabetics.
HbA1c(%) Average Blood Glucose (mg/dL)
4 60
5 90
6 120
7 150
8 180
9 210
10 240
11 270
12 300
13 330