Diagnosis is Type 2 Diabetes Mellitus (T2DM).
1. Definition
Type 2 diabetes mellitus is a chronic metabolic disorder characterized by insulin resistance and progressive pancreatic beta-cell dysfunction, resulting in persistent hyperglycemia.
It is the most common form of diabetes mellitus.
2. Epidemiology
1. T2DM accounts for the majority of diabetes cases worldwide
2. Its prevalence increases with overweight, obesity, physical inactivity, and advancing age
3. It has a strong genetic and familial predisposition
4. It is increasingly diagnosed in younger adults and adolescents
3. Pathophysiology
1. Peripheral insulin resistance develops in skeletal muscle and adipose tissue
2. The pancreas initially compensates with increased insulin secretion
3. Progressive beta-cell dysfunction reduces insulin secretion
4. Hepatic glucose production increases
5. Persistent hyperglycemia develops
6. Chronic hyperglycemia and associated metabolic abnormalities contribute to microvascular and macrovascular complications
4. Risk Factors
1. Overweight or obesity
2. Physical inactivity
3. Family history of diabetes
4. Increasing age
5. Hypertension
6. Dyslipidemia
7. History of gestational diabetes
8. Polycystic ovary syndrome
9. Cardiovascular disease
10. Other conditions associated with insulin resistance
5. Clinical Features
5.1 Classic Hyperglycemic Symptoms
1. Polyuria
2. Polydipsia
3. Polyphagia
4. Fatigue
5. Blurred vision
6. Unintentional weight loss may occur with more severe hyperglycemia
5.2 Signs of Insulin Resistance
1. Central obesity
2. Acanthosis nigricans
5.3 Features Suggesting Complications
1. Recurrent infections
2. Peripheral neuropathic symptoms
3. Foot ulcers
4. Erectile dysfunction
5. Visual impairment
6. Symptoms of cardiovascular or peripheral arterial disease
6. Screening
1. Screening for prediabetes and T2DM should begin at age 35 years for adults without other indications for earlier testing
2. Screen adults of any age with overweight or obesity and one or more additional diabetes risk factors
3. People with prediabetes should generally be tested yearly
4. If screening is normal, repeat testing at least every 3 years, or sooner depending on symptoms and risk factors
7. Diagnosis
Diabetes is diagnosed by any of the following:
1. HbA1c ≥6.5%
2. Fasting plasma glucose ≥126 mg/dL
3. 2-hour plasma glucose ≥200 mg/dL during a 75-g oral glucose tolerance test
4. Random plasma glucose ≥200 mg/dL in a patient with classic symptoms of hyperglycemia or hyperglycemic crisis
In the absence of unequivocal hyperglycemia, two abnormal test results are required for confirmation. These may be two different abnormal tests obtained at the same time or at different times, or the same abnormal test repeated.
This patient has both a fasting plasma glucose of 156 mg/dL and an HbA1c of 8.2%, so the diagnosis of diabetes is confirmed.
7.1 Prediabetes
1. HbA1c: 5.7 to 6.4%
2. Fasting plasma glucose: 100 to 125 mg/dL
3. 2-hour plasma glucose: 140 to 199 mg/dL during a 75-g OGTT
8. Initial Evaluation
8.1 History
1. Hyperglycemic symptoms
2. Duration and severity of symptoms
3. Family history of diabetes and cardiovascular disease
4. Diet and physical activity
5. Medication review
6. Cardiovascular and renal history
7. Smoking and alcohol history
8. Symptoms of neuropathy, retinopathy, or peripheral arterial disease
8.2 Examination
1. BMI and weight
2. Blood pressure
3. Signs of insulin resistance
4. Cardiovascular examination
5. Comprehensive foot examination
6. Assessment for peripheral neuropathy
8.3 Baseline Investigations
1. HbA1c
2. Serum creatinine and eGFR
3. Urine albumin-to-creatinine ratio (UACR)
4. Lipid profile
5. Liver biochemical tests when clinically appropriate
6. Additional testing for alternative or secondary causes of diabetes when indicated
9. Complications
9.1 Microvascular Complications
1. Diabetic retinopathy
2. Diabetic kidney disease
3. Diabetic peripheral and autonomic neuropathy
9.2 Macrovascular Complications
1. Coronary artery disease
2. Cerebrovascular disease
3. Peripheral arterial disease
9.3 Acute Complications
1. Hyperosmolar hyperglycemic state (HHS)
2. Diabetic ketoacidosis (DKA) can occur in T2DM, although it is less typical
3. Hypoglycemia related to glucose-lowering therapy
10. Glycemic Targets
10.1 Most Nonpregnant Adults
1. An HbA1c target <7% is appropriate for many adults
2. Glycemic targets should be individualized
10.2 More Stringent Targets
An HbA1c target such as <6.5% may be appropriate when safely achievable in selected patients with:
1. Good overall health and function
2. Low hypoglycemia risk
3. Low treatment burden
4. Few significant comorbidities
10.3 Less Stringent Targets
Less stringent targets may be appropriate in patients with:
1. Significant comorbidity
2. Frailty
3. Cognitive or functional impairment
4. High hypoglycemia risk
5. Greater treatment burden than expected benefit
11. Management
11.1 Lifestyle and Weight Management
Lifestyle intervention is recommended for all patients.
1. Use an individualized, nutritionally balanced eating pattern emphasizing minimally processed and nutrient-dense foods
2. Reduce excess caloric intake and refined carbohydrates when appropriate
3. Encourage weight reduction in patients with overweight or obesity
4. Aim for at least 150 minutes per week of moderate-to-vigorous aerobic activity, spread over at least 3 days
5. Perform resistance exercise 2 to 3 times per week
6. Reduce prolonged sedentary behavior
Weight reduction improves glycemic control and overall cardiometabolic risk.
11.2 Pharmacologic Therapy
Medication selection should be individualized according to:
1. Glycemic effectiveness
2. Obesity and weight goals
3. Atherosclerotic cardiovascular disease or high cardiovascular risk
4. Heart failure
5. Chronic kidney disease
6. Hypoglycemia risk
7. Adverse effects
8. Cost and access
9. Patient preference
Metformin
1. Metformin remains a commonly used initial glucose-lowering medication when appropriate
2. It is effective, inexpensive, and has a low risk of hypoglycemia
3. It is generally weight neutral or may produce modest weight loss
4. Do not initiate metformin when eGFR is <45 mL/min/1.73 m²
5. In patients already taking metformin, reduce or reassess the dose when eGFR falls below 45 mL/min/1.73 m²
6. Discontinue metformin when eGFR is <30 mL/min/1.73 m²
7. Long-term use may be associated with vitamin B12 deficiency
GLP-1 Receptor Agonists and Dual GIP/GLP-1 Receptor Agonists
1. Particularly useful in patients with T2DM and overweight or obesity
2. Agents such as semaglutide and tirzepatide have high weight-loss efficacy
3. GLP-1 receptor agonists with demonstrated cardiovascular benefit should be prioritized when appropriate in patients with established or high-risk ASCVD
4. These therapies have a low intrinsic risk of hypoglycemia unless combined with insulin or insulin secretagogues
SGLT2 Inhibitors
1. Particularly important in patients with heart failure or chronic kidney disease
2. Provide cardiovascular and renal protection in appropriate patients
3. Benefits for heart failure and CKD may justify use irrespective of HbA1c
4. Important adverse effects include genital mycotic infections and volume depletion
5. Rare euglycemic DKA may occur
Other Options
1. DPP-4 inhibitors
2. Sulfonylureas
3. Thiazolidinediones
4. Insulin
For this patient, lifestyle and weight-management therapy should begin immediately. Pharmacologic therapy is also indicated. Metformin is a reasonable option because renal function is normal. A GLP-1 receptor agonist or dual GIP/GLP-1 receptor agonist is particularly attractive when substantial weight loss is a major treatment goal. Because he has symptoms of hyperglycemia, insulin may be considered, but his HbA1c of 8.2% and fasting glucose of 156 mg/dL do not by themselves mandate insulin therapy in the absence of severe hyperglycemia, catabolic features, or hyperglycemic crisis.
11.3 When to Consider Insulin
Insulin should be considered when:
1. Symptoms of hyperglycemia are present
2. HbA1c >10%
3. Blood glucose is ≥300 mg/dL
4. Catabolic features are present, such as unexplained weight loss or ketosis
5. There is a hyperglycemic crisis
In adults with T2DM without evidence of severe insulin deficiency, severe hyperglycemia, or hyperglycemic crisis, GLP-1-based therapy is generally preferred to insulin as initial or add-on injectable therapy.
12. Monitoring and Complication Screening
12.1 Glycemic Monitoring
1. Assess HbA1c approximately every 3 months when glycemic goals are not being met or treatment has recently changed
2. Once stable and at goal, assess glycemic status at least twice yearly
12.2 Retinopathy
1. Perform a dilated comprehensive eye examination at the time of diagnosis of T2DM
2. If examinations remain normal and glycemia is controlled, screening every 1 to 2 years may be considered
3. Retinopathy requires at least annual or more frequent follow-up depending on severity
12.3 Kidney Disease
1. Assess UACR and eGFR at least annually in all patients with T2DM
2. Monitor more frequently when CKD is present
12.4 Neuropathy and Foot Care
1. Assess for peripheral neuropathy at diagnosis and at least annually
2. Perform 10-g monofilament testing annually to identify feet at risk for ulceration and amputation
3. Perform a comprehensive foot examination at least annually
4. Inspect the feet at every visit in patients with sensory loss or a history of ulceration or amputation
13. Cardiovascular and Renal Protection
1. Optimize blood pressure control
2. Treat dyslipidemia with appropriate statin therapy
3. Encourage smoking cessation
4. Use an ACE inhibitor or ARB when indicated, particularly in patients with hypertension and albuminuria
5. Use SGLT2 inhibitors in appropriate patients with CKD or heart failure
6. Use GLP-1 receptor agonists with demonstrated cardiovascular benefit in appropriate patients with established or high-risk ASCVD
7. Maintain age-appropriate vaccination
8. Address obesity as an important component of cardiovascular risk reduction
Because this patient is 52 years old with diabetes and additional ASCVD risk factors, including hypertension and dyslipidemia, high-intensity statin therapy is recommended if tolerated, with a goal of reducing LDL cholesterol by at least 50% from baseline and achieving an LDL cholesterol level <70 mg/dL for primary prevention.
14. Key Clinical Insight
Obesity + polyuria + polydipsia + acanthosis nigricans + elevated fasting glucose and HbA1c strongly indicate type 2 diabetes mellitus with insulin resistance.
Fasting plasma glucose ≥126 mg/dL or HbA1c ≥6.5% meets a diagnostic threshold for diabetes. In the absence of unequivocal hyperglycemia, two abnormal results confirm the diagnosis.
Management should address not only glycemia but also weight, cardiovascular risk, kidney protection, blood pressure, and dyslipidemia.
References
1. American Diabetes Association Professional Practice Committee for Diabetes. 2. Diagnosis and Classification of Diabetes: Standards of Care in Diabetes 2026. Diabetes Care. 2026;49(Suppl 1):S27-S49. doi:10.2337/dc26-S002.
2. American Diabetes Association Professional Practice Committee for Diabetes. 5. Facilitating Positive Health Behaviors and Well-being to Improve Health Outcomes: Standards of Care in Diabetes 2026. Diabetes Care. 2026;49(Suppl 1):S89-S131. doi:10.2337/dc26-S005.
3. American Diabetes Association Professional Practice Committee for Diabetes. 6. Glycemic Goals, Hypoglycemia, and Hyperglycemic Crises: Standards of Care in Diabetes 2026. Diabetes Care. 2026;49(Suppl 1):S132-S149. doi:10.2337/dc26-S006.
4. American Diabetes Association Professional Practice Committee for Diabetes. 9. Pharmacologic Approaches to Glycemic Treatment: Standards of Care in Diabetes 2026. Diabetes Care. 2026;49(Suppl 1):S183-S215. doi:10.2337/dc26-S009.
5. American Diabetes Association Professional Practice Committee for Diabetes. 10. Cardiovascular Disease and Risk Management: Standards of Care in Diabetes 2026. Diabetes Care. 2026;49(Suppl 1):S216-S245. doi:10.2337/dc26-S010.
6. American Diabetes Association Professional Practice Committee for Diabetes. 11. Chronic Kidney Disease and Risk Management: Standards of Care in Diabetes 2026. Diabetes Care. 2026;49(Suppl 1):S246-S260. doi:10.2337/dc26-S011.
7. American Diabetes Association Professional Practice Committee for Diabetes. 12. Retinopathy, Neuropathy, and Foot Care: Standards of Care in Diabetes 2026. Diabetes Care. 2026;49(Suppl 1):S261-S276. doi:10.2337/dc26-S012.