What you carry at this position in your DNA and what research says about it.
Blood Sugar Levels: 10/10 evidence, 13 publications.
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Sample genotype (not yours): G/G
Optimal Blood Sugar and Lower Diabetes Risk
Two copies of the protective G allele are linked to lower fasting blood sugar and HbA1c levels. This genotype is associated with highly efficient insulin secretion and a reduced risk of type 2 diabetes.
What this genotype means: Lower fasting blood sugar levels; More efficient insulin secretion; Reduced risk of type 2 diabetes.
Sample genotype (not yours): G/T
Typical Blood Sugar and Diabetes Risk
A combination of one protective G allele and one risk T allele results in typical blood sugar levels. Metabolic risk and insulin secretion capacity are generally average.
What this genotype means: Average fasting blood sugar levels; Typical insulin secretion; Standard baseline diabetes risk.
Sample genotype (not yours): T/T
Slightly Higher Blood Sugar and Diabetes Risk
Two copies of the T allele are associated with slightly elevated fasting blood sugar and HbA1c. This genotype is linked to a modest increase in type 2 diabetes risk due to reduced insulin secretion.
What this genotype means: Slightly higher fasting blood sugar; Modestly increased risk of type 2 diabetes; Slightly reduced insulin secretion capacity.
Gene function and biological role
Gene Function: The DGKB gene encodes diacylglycerol kinase beta, an enzyme that regulates diacylglycerol, a crucial lipid messenger in cellular signaling. In pancreatic beta-cells, this pathway is essential for coupling glucose detection to insulin secretion. Variations in DGKB expression can disrupt this delicate balance, leading to impaired glucose homeostasis. Consequently, this gene is a well-established locus influencing fasting blood sugar levels and long-term metabolic health.
Variant Impact: The rs2191349 variant is an intergenic genetic marker located near the DGKB gene on chromosome 7. This variant acts as an expression quantitative trait locus, meaning it influences how actively the nearby DGKB gene is expressed in pancreatic tissues. The T allele of this variant is consistently associated with slightly higher fasting blood glucose levels. It also correlates with elevated HbA1c levels and a modest increase in the risk of developing type 2 diabetes. Conversely, the G allele is linked to better beta-cell function and lower blood sugar.
Key Insight: A single letter change near the DGKB gene can subtly alter how the pancreas responds to glucose, demonstrating how minor genetic variations influence daily blood sugar levels.
Location: DGKB. Chromosome 7 · 7p21.2 · 15.0 Mb
Estimated prevalence by population
Global 21.0%; European 21.0%; African 18.2%; East Asian 10.2%; South Asian 14.3%; Americas 26.7%; Ashkenazi 19.8%; Finnish 31.5%; Middle Eastern 25.3%; Amish 28.9%.
Estimated GG genotype frequency.
Global 49.1%; European 49.6%; African 48.9%; East Asian 43.4%; South Asian 47.0%; Americas 49.9%; Ashkenazi 49.4%; Finnish 49.3%; Middle Eastern 50.0%; Amish 49.7%.
Estimated GT genotype frequency.
Global 29.9%; European 29.4%; African 32.9%; East Asian 46.4%; South Asian 38.7%; Americas 23.3%; Ashkenazi 30.7%; Finnish 19.3%; Middle Eastern 24.7%; Amish 21.4%.
Estimated TT genotype frequency.
Showing effects for G/G genotype
Cardiovascular & Metabolic
Diabetes & Glycemic Traits
Fasting Glucose. Evidence: 10/10. Source: PMID 20081858. Lower Levels.
HbA1c. Evidence: 8/10. Source: PMID 28898252. Lower Levels.
Type 2 Diabetes. Evidence: 8/10. Source: PMID 28869590. Lower Risk.
Beta-Cell Function. Evidence: 6/10. Source: PMID 20081858. Higher Function.
Showing effects for G/T genotype
Fasting Glucose. Evidence: 10/10. Source: PMID 20081858. Typical Levels.
HbA1c. Evidence: 8/10. Source: PMID 28898252. Typical Levels.
Type 2 Diabetes. Evidence: 8/10. Source: PMID 28869590. Typical Risk.
Beta-Cell Function. Evidence: 6/10. Source: PMID 20081858. Typical Function.
Showing effects for T/T genotype
Fasting Glucose. Evidence: 10/10. Source: PMID 20081858. Slightly Higher.
HbA1c. Evidence: 8/10. Source: PMID 28898252. Slightly Higher.
Type 2 Diabetes. Evidence: 8/10. Source: PMID 28869590. Slightly Higher Risk.
Beta-Cell Function. Evidence: 6/10. Source: PMID 20081858. Slightly Lower.
What this genotype means for the people who carry it
Sample genotype: GG (Homozygous)
Possessing two copies of the G allele is highly favorable for metabolic health. Large-scale genetic studies show that this genotype is associated with lower fasting blood glucose levels. This protective effect extends to long-term blood sugar control, as reflected by lower average HbA1c levels. The biological mechanism involves enhanced pancreatic beta-cell function, allowing the body to secrete insulin more effectively in response to glucose. Consequently, individuals with this genotype have a significantly lower risk of developing type 2 diabetes over their lifetime. Maintaining a balanced diet and active lifestyle further complements this natural genetic advantage.
Lower fasting blood sugar levels; More efficient insulin secretion; Reduced risk of type 2 diabetes.
Sample genotype: GT (Heterozygous)
A balanced genetic profile with one protective G allele and one risk T allele represents the typical population average. Fasting blood glucose and long-term HbA1c levels are generally within the normal, average range for the population. Pancreatic beta-cell function and insulin secretion capacity are also typical, showing no major genetic impairment. The risk of developing type 2 diabetes remains at the baseline population level. Because this is a common genetic profile, standard healthy lifestyle choices like regular exercise and a balanced diet are highly effective for maintaining optimal metabolic health.
Average fasting blood sugar levels; Typical insulin secretion; Standard baseline diabetes risk.
Sample genotype: TT (Homozygous)
Inheriting two copies of the T allele is associated with a subtle but consistent increase in fasting blood sugar levels. This genetic profile is also linked to slightly higher HbA1c, which measures average blood sugar over several months. The underlying mechanism is a mild reduction in pancreatic beta-cell function, making insulin secretion slightly less efficient. Over time, this can contribute to a modestly elevated risk of developing type 2 diabetes. However, because the individual effect of this variant is small, proactive lifestyle habits such as managing carbohydrate intake and staying active can easily offset this genetic predisposition.
Slightly higher fasting blood sugar; Modestly increased risk of type 2 diabetes; Slightly reduced insulin secretion capacity.
Variants with shared genetic architecture
rs17168486 · DGKB Gene · Chr 7 · Type 2 Diabetes Risk
rs11558471 · SLC30A8 Gene · Chr 8 · Type 2 Diabetes Risk
rs11708067 · ADCY5 Gene · Chr 3 · Type 2 Diabetes Risk
Content updated August 2026.
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