The risk factors for type 2 diabetes span genetics, lifestyle, body composition, and several medical conditions. Some you can change, others you can’t, but knowing where you stand helps you act early. The American Diabetes Association recommends all adults begin screening at age 35, and sooner if other risk factors are present.
Body Weight and Where You Carry It
Carrying excess weight is the single most common modifiable risk factor for type 2 diabetes. But the number on the scale tells only part of the story. Where your body stores fat matters just as much. Fat that accumulates around the abdomen, sometimes called visceral fat, is more metabolically active and more disruptive to how your body processes insulin than fat stored in your hips or thighs.
The CDC uses waist circumference as a practical marker: women with a waist measuring more than 35 inches and men with a waist over 40 inches face higher risk for metabolic complications, including type 2 diabetes. These thresholds apply to the general population, but they shift for certain ethnic groups. For Asian Americans, the recommended BMI cutoff for diabetes screening is 23 or above, compared to 25 for most other populations, because metabolic problems tend to develop at lower body weights in this group.
Family History and Genetics
Having a close relative with type 2 diabetes substantially raises your own risk, and the more relatives affected, the higher that risk climbs. A large European study found that having any first-degree family member (a parent or sibling) with type 2 diabetes increased a person’s risk roughly 2.5-fold. If both parents have it, the risk jumps to about five times that of someone with no family history. Three affected family members push the risk nearly sixfold.
This isn’t purely about shared genes. Families also share eating patterns, activity levels, and environments. Researchers in that study found that the elevated risk from family history persisted even after accounting for weight, lifestyle, and known genetic markers, which suggests something beyond measurable factors is at play. If type 2 diabetes runs in your family, earlier and more frequent screening makes sense.
Age and Ethnicity
Risk rises with age, and being 45 or older is a recognized threshold. This is partly because insulin resistance tends to increase as you get older, and partly because years of gradual metabolic wear accumulate. That said, type 2 diabetes is increasingly diagnosed in younger adults and even adolescents, particularly when other risk factors are present.
Certain racial and ethnic groups face disproportionately higher risk. African American, Hispanic and Latino, American Indian, Alaska Native, some Pacific Islander, and some Asian American populations all have elevated rates of type 2 diabetes compared to white Americans. These disparities reflect a combination of genetic susceptibility, socioeconomic factors that shape diet and activity, and differences in access to preventive care.
Physical Inactivity
Exercising fewer than three times a week is a standalone risk factor. Physical activity improves your cells’ ability to respond to insulin, lowers blood sugar independently of weight loss, and reduces visceral fat. The CDC recommends at least 150 minutes of moderate-intensity activity per week, which works out to about 30 minutes five days a week. Walking briskly, cycling, swimming, or anything that elevates your heart rate enough to make conversation slightly harder all count.
The protective effect of exercise holds even if you don’t lose significant weight. Regular movement changes how your muscles take up glucose and how your liver manages its sugar stores, which means it helps regardless of your starting body size.
Prediabetes
Prediabetes, where blood sugar is elevated but not yet in the diabetic range, is both a warning sign and a risk factor in its own right. Roughly 5 to 10 percent of people with prediabetes progress to full type 2 diabetes each year, though the rate varies by population. Without intervention, the trajectory is clear: most people with prediabetes will eventually develop type 2 diabetes if nothing changes.
The encouraging flip side is that prediabetes is the stage where lifestyle changes have the most dramatic impact. Modest weight loss (5 to 7 percent of body weight) combined with regular physical activity can cut progression rates significantly. If you’ve been told your blood sugar is “borderline,” that’s not a neutral finding. It’s an active risk factor worth addressing.
Gestational Diabetes
Women who develop diabetes during pregnancy face a lasting increase in risk. Approximately 20 to 50 percent of women with a history of gestational diabetes go on to develop type 2 diabetes within 10 years after delivery, and the risk can reach as high as 70 percent over longer follow-up periods. Giving birth to a baby weighing over 9 pounds is also flagged as a risk factor, even if gestational diabetes wasn’t formally diagnosed.
The metabolic stress of pregnancy can unmask insulin resistance that was already developing, essentially accelerating a process that might have taken years to surface otherwise. Women with a history of gestational diabetes benefit from annual screening rather than waiting for the standard intervals.
Polycystic Ovary Syndrome (PCOS)
PCOS is one of the most underrecognized pathways to type 2 diabetes. The condition is rooted in hormonal imbalance, but insulin resistance is a core feature for most women who have it. Their bodies produce insulin normally but can’t use it efficiently, which forces the pancreas to work harder and eventually leads to blood sugar problems. More than half of women with PCOS develop type 2 diabetes by age 40, making it one of the strongest medical risk factors outside of prediabetes itself.
Sleep Apnea and Poor Sleep
Obstructive sleep apnea, where breathing repeatedly stops and restarts during sleep, has a well-documented link to diabetes risk. The mechanism involves two things that happen during apnea episodes: oxygen levels drop intermittently, and sleep architecture gets fragmented. Both independently disrupt glucose metabolism.
In controlled experiments with healthy volunteers, just five hours of intermittent drops in oxygen reduced insulin sensitivity by 17 percent. Fragmenting deep sleep with noise (without changing total sleep time) reduced insulin sensitivity by 20 to 25 percent. Over months and years, these nightly disruptions push the body toward chronic insulin resistance. Sleep apnea also triggers a persistent state of elevated stress-hormone signaling that suppresses insulin secretion and alters how the liver and fat cells manage energy. If you snore heavily, wake unrefreshed, or have been told you stop breathing at night, the metabolic consequences extend well beyond fatigue.
Non-Alcoholic Fatty Liver Disease
Fat buildup in the liver, unrelated to alcohol use, is both a consequence of insulin resistance and a driver of it. The liver plays a central role in regulating blood sugar, and when it becomes infiltrated with fat, its ability to respond to insulin deteriorates. This creates a feedback loop: insulin resistance promotes liver fat, and liver fat worsens insulin resistance. The CDC lists non-alcoholic fatty liver disease as a distinct risk factor for type 2 diabetes, and it frequently coexists with excess weight, inactivity, and prediabetes.
How Multiple Risk Factors Interact
These risk factors don’t operate in isolation. A person who is sedentary, carries abdominal weight, has a parent with diabetes, and sleeps poorly isn’t simply adding risks together. The factors amplify each other. Visceral fat worsens insulin resistance, which promotes liver fat, which further impairs glucose regulation, which makes weight loss harder. Family history may lower the threshold at which any of these lifestyle factors become dangerous.
This is why screening guidelines don’t rely on a single criterion. The ADA recommends testing all adults starting at age 35, but testing earlier for anyone with a BMI of 25 or above (23 for Asian Americans) who has at least one additional risk factor. If your results come back normal, repeat testing every three years is typical, or sooner if your risk profile changes.