Type 2 diabetes mellitus in adults

Overview 
Theory 
Diagnosis 
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Your Organizational Guidance

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Diabetes Mellitus Type 2Published by: Domus Medica | SSMGLast published: 2017Diabète sucré de type 2Published by: SSMG | Domus MedicaLast published: 2017

Individualized risk-to-benefit ratio should be considered in screening, intervention, and monitoring to lower the risk of type 2 diabetes and associated comorbidities.[2] Multiple factors, including age, body mass index (BMI), and other comorbidities, may influence the risk of progression to diabetes and lifetime risk of complications. Prediabetes is associated with increased cardiovascular (CV) disease and mortality, which emphasizes the importance of attending to CV risk in this population.[2]

Screening for prediabetes

Screening for prediabetes and type 2 diabetes risk through an assessment of risk factors is recommended to guide whether to perform a diagnostic test for prediabetes. See Screening.

Testing high-risk adults for prediabetes is warranted because the laboratory assessment is safe and reasonable in cost, substantial time exists before the development of type 2 diabetes and its complications during which one can intervene, and there are effective approaches delaying type 2 diabetes in those with prediabetes with a hemoglobin A1c (HbA1c) of 5.7% to 6.4% (39-47 mmol/mol), impaired glucose tolerance (IGT), or impaired fasting glucose (IFG).[2]

Lifestyle changes

Lifestyle factors (obesity, physical inactivity, stress, and smoking) seem to be the main drivers of the current diabetes epidemic. Although pharmacologic approaches can reverse prediabetes, lifestyle modification provides the strongest evidence of effectiveness and should remain the recommended approach.[55] Lifestyle interventions have been shown to be especially effective in older adults, while metformin has proved less effective as primary prevention in this population.[25] Evidence shows that a combination of low-risk lifestyle behaviors, including maintaining a healthy body weight, healthy diet, regular exercise, smoking abstinence or cessation, and light alcohol consumption, is associated with a lower risk of incident type 2 diabetes.[56]

With aggressive prevention of obesity in all age groups, type 2 diabetes is potentially preventable.[57][58] Several clinical trials have shown that weight loss is associated with delayed or decreased onset of diabetes in high-risk adults.[35][36][37][38] [ ] The strongest evidence for diabetes prevention in the US comes from the Diabetes Prevention Program (DPP) trial, which demonstrated that intensive lifestyle intervention (with the goals of at least 7% weight loss and at least 150 minutes of moderate-intensity physical activity per week) via a structured program could reduce the risk of incident type 2 diabetes by 58% over 3 years.[36] Although weight loss was the most important factor, achieving the behavioral goal of at least 150 minutes of physical activity per week, even without achieving the weight loss goal, reduced the incidence of type 2 diabetes by 44%.[36] The delivery of such programs in a digital format has demonstrated clinical effectiveness and has significant potential for widespread dissemination.[59] The American Diabetes Association (ADA) recommends referring adults with overweight or obesity at high risk of type 2 diabetes to an intensive lifestyle behavior change program to achieve and maintain a weight reduction of at least 7% of initial body weight through healthy reduced-calorie diet and ≥150 minutes/week of moderate-intensity physical activity.[2] In addition to aerobic activity, a physical activity plan designed to prevent diabetes should include resistance training. Breaking up prolonged sedentary time should also be encouraged, as it is associated with moderately lower postprandial glucose levels.[2]

In the US, the Centers for Disease Control and Prevention (CDC) has developed the National Diabetes Prevention Program (National DPP), a resource designed to bring evidence-based lifestyle change programs for preventing type 2 diabetes to communities.[60] One key feature of the National DPP is the lifestyle change program, which focuses on nutritional and physical activity modification for individuals with prediabetes and those who are at risk for type 2 diabetes. The year-long program follows a research-based curriculum that starts with weekly group meetings for the first 6 months, followed by routine upkeep sessions to keep participants on track. To be eligible for this program, individuals must meet all four of the following criteria:[60]

Be ages 18 years or older
Have a BMI ≥25 kg/m² (or BMI ≥23 kg/m² if self-identified as Asian)
Not be previously diagnosed with type 1 or type 2 diabetes
Not be pregnant.

They must also meet one of the following requirements:

Have had a blood test result in the prediabetes range within the past year. This includes any of these tests and results:
- HbA1c: 5.7% to 6.4% (39-46 mmol/mol)
- Fasting plasma glucose: 100-125 mg/dL (5.6-6.9 mmol/L)
- 2-hour plasma glucose (after a 75 g glucose load): 140-199 mg/dL (7.8-11.0 mmol/L).
Have been previously diagnosed with gestational diabetes
Have received a high-risk result (score of 5 or higher) on the Prediabetes Risk Test. CDC: Prediabetes Risk Test Opens in new window

A variety of eating patterns can be considered to prevent type 2 diabetes in individuals with prediabetes. The ADA recommends that macronutrient distribution should be based on an individualized assessment of current eating patterns, preferences, and metabolic goals.[2] Evidence suggests that the overall quality of food consumed, with an emphasis on whole grains, legumes, nuts, fruits, and vegetables and minimal refined and processed foods, is also associated with a lower risk of type 2 diabetes.[2] One large meta-analysis found that the consumption of meat, particularly processed meat and unprocessed red meat, is a risk factor for developing type 2 diabetes across populations.[61] Higher consumption of sugar-sweetened beverages has also been linked to an increased risk of developing type 2 diabetes; sugary drink consumption should therefore be minimized.[62] Counseling by a registered dietitian nutritionist has been shown to help individuals with prediabetes improve eating habits.[2]

According to the World Health Organization (WHO), smoking cessation reduces the long-term risk of developing type 2 diabetes, despite potential short-term weight gain. Health benefits increase with longer duration of quitting.[49] The WHO recommends population-level and pharmacologic interventions to ensure access to comprehensive cessation support.[49] See Smoking cessation.

Pharmacologic preventive treatment

Because weight loss through behavior changes in diet and physical activity can be difficult to maintain long term, people at high risk of type 2 diabetes may benefit from additional support and pharmacotherapeutic options, if needed. The ADA advises that pharmacotherapy (e.g., for weight management, minimizing the progression of hyperglycemia, and CV risk reduction) may be considered to support person-centered care goals.[2] Several pharmacologic agents, including metformin, orlistat, glucagon-like peptide-1 (GLP-1) receptor agonists, alpha-glucosidase inhibitors, thiazolidinediones, and insulin, have been shown to reduce progression from prediabetes to diabetes in specific populations.[2][63][64][65][66][67] [ ] [ ] [ ] Dapagliflozin (a sodium-glucose cotransporter-2 [SGLT2] inhibitor) reduced the incidence of new-onset type 2 diabetes in patients with chronic kidney disease or heart failure compared with placebo, although no improvement in glycemic control was observed.[68]

Lifestyle change and/or metformin are preferred for most patients.[69][70][71][72][73] The ADA recommends that metformin should be considered in adults at high risk of type 2 diabetes, especially those ages 25-59 years with BMI ≥35 kg/m², higher fasting plasma glucose (e.g., ≥110 mg/dL [≥6 mmol/L]), and higher HbA1c (e.g., ≥6.0% [≥42 mmol/mol]), and in individuals with prior gestational diabetes mellitus.[2]

More aggressive multi-agent pharmacologic approaches remain controversial.[74] The ADA advises that more intensive preventive approaches should be considered in individuals who are at particularly high risk of progression to diabetes, including individuals with BMI ≥35 kg/m², those at higher glucose levels (e.g., fasting plasma glucose 110-125 mg/dL [6.1-6.9 mmol/L], 2-hour post-challenge glucose 173-199 mg/dL [9.6-11.0 mmol/L], HbA1c ≥6.0% [≥42 mmol/mol]), and individuals with a history of gestational diabetes mellitus.[2]

CV risk reduction

Prediabetes is associated with heightened CV risk; therefore, screening for and treatment of modifiable risk factors for CV disease are suggested.[75][76][77] One study investigating the effect of blood pressure (BP) lowering on the risk of new-onset type 2 diabetes found that reducing systolic BP by 5 mmHg decreased the risk of type 2 diabetes by 11%.[78] Antihypertensive treatment with ACE inhibitors and angiotensin-II receptor agonists led to more favorable outcomes than treatment with beta-blockers, thiazide diuretics, or calcium-channel blockers. Another study found that valsartan plus lifestyle modification produced a reduction in the incidence of diabetes but did not reduce the rate of CV events.[79]

Statin therapy may increase the risk of type 2 diabetes in people at high risk of developing type 2 diabetes.[80] In such individuals, glucose status should be monitored regularly and diabetes prevention approaches reinforced. It is not recommended that statins be discontinued for this adverse effect.[2]

Secondary prevention

Although the risk of macrovascular complications can be reduced by over 50% using effective multifactorial interventions, a US national survey found more than half of outpatients over age 50 years with diabetes and hypertension did not receive an antiplatelet agent, statin therapy, or ACE inhibitor/angiotensin-II receptor antagonist.[447][448] More evidence indicates that sodium-glucose cotransporter-2 (SGLT2) inhibitor (or dual SGLT1/SGLT2 inhibitor) and glucagon-like peptide-1 (GLP-1) receptor agonist therapy can play a significant role in reducing future risk in individuals with comorbid atherosclerotic cardiovascular disease, heart failure, or chronic kidney disease (CKD), and use of one these agents should be strongly considered if not contraindicated in the secondary prevention of macrovascular complications.[2][106][141]

Other preventive measures include:[2][449][450]

Annual influenza immunizations
Vaccination against pneumococcal disease; there are two types of vaccines available in the US, the pneumococcal conjugate vaccines (PCV13, PCV15, PCV20, and PCV21) and the pneumococcal polysaccharide vaccine (PPSV23), with distinct schedules for children and adults
Vaccination against COVID-19
Single-dose vaccination against respiratory syncytial virus (RSV) for adults ages ≥75 years and for adults ages 60-74 years with diabetes complicated by CKD, neuropathy, retinopathy, or other end-organ damage, or requiring treatment with insulin or an SGLT2 inhibitor
Vaccination against respiratory syncytial virus for adults ≥60 years (single dose)
Hepatitis B vaccination for unvaccinated adults with diabetes ages 19-59 years; considered for unvaccinated adults with diabetes ages 60 years and older
Regular dental care
Tailored diabetes education.

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Type 2 diabetes mellitus in adults

Primary prevention

Your Organizational Guidance

Secondary prevention