y appropriate for the diagnosis of DM. There is no concordance between the results of these tests.
Diagnosis of Gestational Diabetes Mellitus
Pregnant women not previously known to have diabetes should be tested for GDM at 24 to 28 weeks of gestation. ADA and American College of Obstetrics and Gynecology (ACOG) recommend using either a 1-step or 2-step approach for diagnosing GDM.
75 gm OGTT is performed after an overnight fast. Blood samples are collected at fasting for 1 hour and 2 hours. GDM is diagnosed if fasting glucose meet or exceed 92 mg/dl (5.1 mmol/l), 1-hour serum glucose of 180 mg/dl (10.0 mmol/l) or 2-hour serum glucose of 153 mg/dl (8.5 mmol/l).
- Step one: Perform a 50-gram glucose challenge test irrespective of the last meal. If PG at 1-hour after the load is greater than or equal to 140mg/dl (7.8 mmol/l), proceed to step 2.
- Step 2: 100 g glucose OGTT is performed after overnight fasting. Cut off values are fasting PG 95 or 105 mg/dl (5.5/5.8 mmol/l), 1-hour PG of 180 or 190 mg/dl (10.0/10.6 mmol/l), 2-hour PG of 155 or 165 mg/dl (8.6/9.2 mmol/l) or 3-hour PG of 140 or 145 mg/dl (7.8/8.0 mmol/l). GDM is diagnosed if two or more PG levels equal to or exceed these cutoffs.
Treatment / Management
For both T1DM and T2DM, the cornerstone of therapy is diet and exercise.
A diet low in saturated fat, refined carbohydrates, high fructose corn syrup, and high in fiber and monounsaturated fats needs to be encouraged. Aerobic exercise for a duration of 90 to 150 minutes per week is also beneficial. The major target in T2DM patients, who are obese, is weight loss.
If adequate glycemia cannot be achieved, metformin is the first-line therapy. Following metformin, many other therapies such as oral sulfonylureas, dipeptidyl peptidase-4 (DPP-4) inhibitors. Glucagon-like peptide-1 (GLP-I) receptor agonists, Sodium-glucose co-transporter-2 (SGLT2) inhibitors, pioglitazone, especially if the patient has fatty liver disease, alpha-glucosidase inhibitors, and insulin, are available. Recent studies have shown that the SGLT2 inhibitor, empagliflozin (EMPA), and the GLP-1 receptor agonist, liraglutide, reduce significant cardiovascular (CV) events and mortality. Hence, in patients with CV disease, these drugs should be considered next. For patients with T1DM, a regime of basal-bolus insulin is the mainstay of therapy. Also, insulin pump therapy is a reasonable choice. Since hypoglycemia portends increased mortality, preference should be given to therapies that do not induce hypoglycemia, for example, DPP-4 Inhibitors, SGLT-2 inhibitors, GLP-I receptor agonists, and pioglitazone with metformin. The other advantages of SGLT-2 inhibitors and GLP-I receptor agonists are a reduction in body weight, blood pressure (BP), and albuminuria.
To reduce microvascular complications in the majority, the goal Hb A1C should be less than 7%. Also, the BP goal should be less than 130/85 mmHg with a preference for angiotensin-converting enzyme (ACE)/angiotensin receptor blocker (ARB) therapy. Fundal exams should be undertaken as proposed by guidelines and urine albumin excretion at least twice a year.
For the lipid panel, the goal should be an LDL-C less than 100 mg/dl if no atherosclerotic cardiovascular disease (ASCVD) or less than 70 mg/dl if ASCVD present. The drug of choice is a statin since these drugs reduce CV events and CV mortality. Consider adding ezetimibe and PCSK9 inhibitors for patients with ASCVD who are not at goal.
Since the different complications and therapies have been detailed in other StatPearls review articles, we have outlined only the principles of therapy.
The list of differential diagnosis of diabetes mellitus consists of various conditions that would exhibit similar signs and symptoms:
- Drug-induced signs and symptoms due to corticosteroids, neuroleptics, pentamidine, etc.
- Genetic aberrations in beta-cell function and insulin action
- Metabolic syndrome (syndrome X)
- Endocrinopathies such as acromegaly, Cushing disease, pheochromocytoma, hypothyroidism, etc.
- Complications of iron overload (hemochromatosis)
- Con